Microsoft Threat Intelligence observed a large-scale npm supply chain attack affecting 140+ packages across the mastra and @mastra scopes on the npm registry. Microsoft shared its findings with the npm security team, and the compromised packages have been removed and the attacker’s publish access to the @mastra scope has been revoked. The compromise originated from the takeover of the ehindero npm maintainer account, which had publish rights across the Mastra ecosystem and was used to publish poisoned package versions that introduced easy-day-js, a malicious typosquat of the popular dayjs library.

Once installed, easy-day-js triggered a postinstall hook that executed an obfuscated dropper script, disabled Transport Layer Security (TLS) certificate verification, contacted attacker-controlled command-and-control (C2) infrastructure, downloaded a second-stage payload, and executed the payload as a detached hidden process. The activity followed a coordinated staged delivery pattern, with a clean bait version published first, followed by a weaponized version and rapid publication of the compromised Mastra packages.

Because the payload executes during installation, any developer workstation or continuous integration and continuous delivery (CI/CD) pipeline that ran npm install or npm update after the compromised versions were published was potentially exposed, regardless of whether the package was imported in application code.  This created risk to credentials, tokens, build environments, and downstream software integrity. Microsoft Defender Antivirus, Microsoft Defender for Endpoint, and Microsoft Defender XDR provide detections and hunting coverage for suspicious Node.js execution, malicious package behavior, reflective code loading, persistence activity and command-and-control communication.

Attack chain overview

At a high level, the attack progressed through six phases:

• Account compromise: The attacker gained control of the ehindero npm account , a listed maintainer with publish rights across the entire @mastra scope.
• Typosquat creation: The attacker published easy-day-js, a package impersonating the legitimate dayjs library (57M+ weekly downloads), using a coordinating anonymous email account ).
• Mass poisoning: Using the compromised account, the attacker published new versions of 140+packages across the @mastra scope, each injected with easy-day-js@^1.11.21 as a new dependency. All poisoned versions were tagged as latest.
• Delivery: Developers and CI/CD pipelines running npm install automatically resolved to the compromised versions. The semantic versioning (SemVer) range ^1.11.21 resolved to 1.11.22, the version containing the malicious postinstall hook.
• Execution: The postinstall hook executed an obfuscated 4,572-byte dropper that disabled TLS verification, dropped tracking markers, and contacted the C2 server.
• Second-stage payload: The dropper fetched executable code from the C2 server, wrote it as a randomly named .js file, and spawned it as a fully detached, window-hidden Node.js process.

Discovery and initial indicators

Microsoft Threat Intelligence identified the compromise through anomalous publishing patterns on the mastra package. All previous versions of mastra (through v1.13.0) were published through GitHub Actions OpenID Connect (OIDC), the legitimate CI/CD pipeline. Version 1.13.1 was manually published by ehindero using a Tutamail address, an anonymous email service.

The only change between mastra@1.13.0 and mastra@1.13.1 was the addition of easy-day-js@^1.11.21 as a dependency. No corresponding code changes were present in the Mastra GitHub repository. Both the compromised publisher (ehindero2016@tutamail.com) and the typosquat publisher (sergey2016@tutamail.com) used the same anonymous email provider, Tutamail.

Dependency injection: the poisoned package.json

The compromised mastra@1.13.1 package.json reveals the injected dependency alongside the anomalous publisher metadata:

The easy-day-js dependency was not present in any prior versions of mastra npm packages. Its addition, paired with the SemVer range ^1.11.21, ensures that the npm resolves to the weaponized 1.11.22 release.

Typosquat analysis: easy-day-js

The easy-day-js package is a deliberate impersonation of the legitimate dayjs library:

Staged delivery pattern

The typosquat used a two-phase delivery strategy:

• Phase 1 (clean bait): easy-day-js@1.11.21 was published at 07:05 UTC on June 16, 2026. This version contained only legitimate dayjs code with no postinstall hook.
• Phase 2 (weaponization): easy-day-js@1.11.22 was published at 01:01 UTC on June 17, 2026, adding the setup.cjs payload and the postinstall hook. The dayjs.min.js file is byte-identical between both versions, confirming only the dropper was added.

The weaponized package.json in version 1.11.22 exposes the postinstall hook:

Obfuscation and payload analysis

Stage 0: Obfuscated dropper (setup.cjs)

The setup.cjs payload is protected with JavaScript obfuscation using rotated string arrays and a custom base64 decoder function:

The obfuscation technique uses a common pattern: an array of 40 Base64-encoded strings is shuffled at initialization using a numeric seed (0x4c11d), then accessed through a decoder function that performs Base64 decoding with character substitution. This prevents static analysis tools from extracting meaningful strings.

Stage 1: String table decryption

Decoding the rotated string array reveals the payload’s true capabilities:

Key decoded strings include the secondary C2 address (23.254.164[.]123:443), Node.js built-in module references (node:child_process, node:os), and file system operations (writeFileSync, rmSync).

Stage 2: Deobfuscated payload logic

After resolving all string references and control flow, the full payload logic emerges as a five-step attack sequence:

TLS bypass to self-deletion

Step 1: Disable TLS verification. The payload sets NODE_TLS_REJECT_UNAUTHORIZED to ‘0’, disabling certificate validation for all HTTPS requests in the Node.js process. This enables communication with the C2 server without valid certificates.

Step 2: Drop filesystem markers. Two tracking files are written to the OS temp directory: $TMPDIR/.pkg_history contains the install path of the compromised package, and $TMPDIR/.pkg_logs contains the package name encoded with XOR 0x80:

Step 3: Fetch second-stage payload. The dropper issues a GET request to hxxps://23.254.164[.]92:8000/update/49890878 and reads the response body as text.

The second-stage payload is a ~41 KB cross-platform Node.js tasking client. Unlike a fire-and-forget stealer, the implant installs sign-in persistence, sends a Start beacon to the C2, then enters a repeated Check poll loop. Tasks returned by the server are dispatched to built-in runners (a Node runner and a Shell runner), and it honors configuration update and exit commands, meaning the operator can push and execute arbitrary follow-on code on the host at any time. On Windows, the payload additionally executes reflective .NET assembly injection for in-memory code execution.

Step 3.A: Windows execution chain. On Windows, the payload performs host reconnaissance and reflective in-memory code execution before establishing persistence.

The payload enumerates all installed applications across three sources—Start Menu entries (Get-StartApps), registry Uninstall keys, and UWP packages (Get-AppxPackage)—to fingerprint the compromised host:

Each enumeration is wrapped in try/catch with silent error handling. The deduplicated results are exfiltrated back to the C2 for victim profiling, enabling the attacker to identify installed security products and high-value targets.

A second PowerShell script receives two C2 endpoint URLs through the SCRIPT_ARGS environment variable. It disables SSL certificate validation and defines an HTTP POST function that Base64-encodes request bodies using a legacy IE8 User-Agent string:

The first C2 request downloads a .NET DLL that is loaded directly into memory via reflection, completely bypassing disk-based detection. The script resolves the Extension.SubRoutine class and invokes its Run2 method with a second downloaded payload, the path to cmd.exe, and the C2 callback address:

This pattern is consistent with process injection, where the payload is injected into a cmd.exe process that communicates back to the C2 over HTTPS (port 443). The entire chain is fileless—no artifacts are written to disk.

Step 3.B: Cross-platform persistence. The implant installs login persistence on all three major operating systems, using a consistent NVM/Node masquerade theme across platforms:

On Windows, the Run key launches a hidden PowerShell process that invokes Node.js:

On Linux, the systemd user unit restarts the implant on failure with a 5-second delay:

All three persistence paths drop the implant as protocal.cjs (a deliberate misspelling) into directories named to mimic legitimate Node.js installations. The value name NvmProtocal, the macOS label com.nvm.protocal, and the Linux unit nvmconf.service are deliberately designed to blend into a developer workstation.

Step 3.C: Collection and exfiltration. The implant performs the following collection before exfiltrating to the C2:

• Cryptocurrency wallet inventory: A hardcoded list of 166 wallet browser-extension IDs (MetaMask, Phantom, Coinbase Wallet, Binance Wallet, TronLink, and others) is matched against installed extensions across Chrome, Edge, and Brave profiles.
• Browser history: Each profile’s History SQLite database is copied to a temp directory prefixed with browser-hist- and queried through node:sqlite.
• Host reconnaissance: Gather hostname, architecture, platform, user ID, installed applications, and running processes.

Collected data is exfiltrated using a custom ICAP-style protocol over HTTPS POST (reqmod, PrimaryUrl, SecondaryUrl headers), with hostnames resolved through node:dns and traffic carrying a spoofed legacy IE8 User-Agent string.

Step 4: Writing and executing the payload. The downloaded code is written to a file with a cryptographically random name (<12 random hex bytes>.js) in the OS temp directory, then spawned as a detached, window-hidden Node.js process using child_process.spawn with unref().

Step 5: Self-deletion. The dropper removes itself (fs.rmSync(__filename)) to eliminate forensic evidence from the installed package directory.

Timeline analysis

Every package published by the ehindero account contained easy-day-js as an injected dependency. Packages last published by GitHub Actions CI/CD or other legitimate maintainers were not affected.

Attack timeline

** Microsoft Threat Intelligence monitoring observed easy-day-js@1.11.22 at 01:07 UTC and mastra@1.13.1 at 01:28 UTC on June 17, 2026

Mitigation and protection guidance

Microsoft recommends the following mitigations to reduce the impact of this threat:

• Review dependency trees for direct or transitive usage of affected @mastra packages at the compromised versions listed above.
• Check for the presence of easy-day-js in node_modules/ or package-lock.json files across your projects and CI/CD environments.
• Pin known-good package versions where possible. For mastra, version 1.13.0 and earlier are unaffected. For @mastra/core, version 1.42.0 and earlier are unaffected.
• Run npm install with –ignore-scripts to prevent automatic execution of postinstall hooks during dependency installation.
• Check systems for indicators of compromise (IOC) artifacts: Look for $TMPDIR/.pkg_history, $TMPDIR/.pkg_logs, and unexpected .js files in the user’s home or temp directories.
• Rotate any credentials, tokens, or API keys that may have been present on systems where the compromised packages were installed.
• Block the C2 IP addresses 23.254.164[.]92 and 23.254.164[.]123 at the network perimeter.
• Audit CI/CD logs for unexpected outbound connections to the C2 IP addresses or suspicious postinstall script execution.
• Enable cloud-delivered protection in Microsoft Defender Antivirus or equivalent antivirus protection.

Microsoft Defender XDR detections

Microsoft Defender XDR customers can refer to the list of applicable detections below. Microsoft Defender XDR coordinates detection, prevention, investigation, and response across endpoints, identities, email, and apps to provide integrated protection against attacks like the threat discussed in this blog.

Microsoft Security Copilot

Security Copilot customers can use the standalone experience to create their own prompts or run the following prebuilt promptbooks to automate incident response or investigation tasks related to this threat:  

• Incident investigation  
• Microsoft User analysis  
• Threat actor profile  
• Threat Intelligence 360 report based on MDTI article  
• Vulnerability impact assessment  

Note that some promptbooks require access to plugins for Microsoft products such as Microsoft Defender XDR or Microsoft Sentinel.  

Advanced hunting

The following KQL queries can be used in Microsoft Defender XDR Advanced Hunting to identify potential exposure to this supply chain compromise.

Detect postinstall execution of setup.cjs

DeviceProcessEvents 
 | where Timestamp > ago(7d) 
 | where FileName in ("node", "node.exe") 
 | where ProcessCommandLine has "setup.cjs" 
     or ProcessCommandLine has "easy-day-js" 
|  where ProcessCommandLine has “--no-warnings” 
 | project Timestamp, DeviceName, AccountName, 
     ProcessCommandLine, FolderPath, InitiatingProcessFileName 
 | sort by Timestamp desc 

Outbound connections to C2 infrastructure

DeviceNetworkEvents
| where Timestamp > ago(7d)
| where RemoteIP in ("23.254.164.92", "23.254.164.123")
| project Timestamp, DeviceName, RemoteIP, RemotePort, RemoteUrl,
    InitiatingProcessFileName, InitiatingProcessCommandLine
| sort by Timestamp desc

Indicators of compromise (IOC)

Network indicators

File indicators

Host indicators

Package indicators

References

Security: mastra@1.13.1 is compromised — malicious postinstall payload via `easy-day-js` dependency · Issue #18046 · mastra-ai/mastra

Microsoft has identified a supply chain attack on the Mastra-AI npm ecosystem, with 80+ packages compromised through npm account takeover. The attacker introduced a phantom dependency into the… | Microsoft Threat Intelligence

This research is provided by Microsoft Defender Security Research, Suriyaraj Natarajan, Sagar Patil, Rajesh Kumar Natarajan, Mahesh Mandava, Arvind Gowda, and with contributions from members of Microsoft Threat Intelligence.

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The post From package to postinstall payload: Inside the Mastra npm supply chain compromise appeared first on Microsoft Security Blog.

The attackers deployed a new Go-based backdoor that uses Microsoft Teams servers for command-and-control.

The post Microsoft Teams Relay Servers Abused in DragonForce Ransomware Attack appeared first on SecurityWeek.

During a recent incident response engagement, our team uncovered a multi-stage WordPress infection that goes beyond the usual file-based malware. The attacker combined a fake plugin, a remote command-and-control server, and two PHP web shells stored directly inside the WordPress database.

The campaign is operated by a Turkish-speaking threat actor and is built around a classic SEO monetization scheme: hidden backlink injection for a Private Blog Network (PBN), most likely tied to the gambling and adult affiliate niche.

Continue reading WordPress PBN Plugin Drops Dual Webshells via Database Injection at Sucuri Blog.

Since late 2025, malware has been spreading rapidly through the Steam Workshop, the gaming platform’s built-in service for players to create and share custom content. The attackers are primarily targeting gamers in China and Russia, aiming to hijack their accounts. To pull this off, they are exploiting Wallpaper Engine – a popular live wallpaper app available on Steam – specifically leveraging its Workshop sharing feature. The malware is hidden inside the wallpaper packages users share with one another. Running one of these compromised wallpapers can lead to a stolen Steam account or leave the victim’s system infected with backdoors or crypto miners.

What is Wallpaper Engine?

Wallpaper Engine is an app that allows you to put animated wallpapers on your desktop. It’s available for both Windows and Android, though our investigation focused strictly on the Windows version. Thanks to a massive Steam community, the app is quite popular, boasting around 100,000 daily active users and nearly a million reviews. It comes with a built-in editor so users can create their own designs, and it supports a few different wallpaper types:

• Videos: MP4, WebM, and other common video formats
• Scenes: interactive wallpapers built inside the app’s own editor
• Web pages: HTML pages powered by JavaScript and CSS, which can also include audio and video elements
• Applications: active windows from third-party Windows-compatible software that Wallpaper Engine sets as the user’s desktop background

That last type, application wallpapers, is where things get risky, because these are essentially standalone programs. They can be anything from mini-games you play right on your desktop, to planners, calendars, system monitors, or widgets tracking your CPU or GPU usage.

Application wallpapers: a built-in security risk

The whole concept of “application wallpapers” essentially allows foreign code to be run directly on your computer. Cybercriminals took note of this feature and started embedding malware right into these types of wallpapers. Because Wallpaper Engine relies on Steam Workshop for content sharing, anyone can create a wallpaper and publish it for the community to download and install for free. Naturally, this setup is a magnet for bad actors.

We discovered dozens of these malicious application wallpapers floating around Steam Workshop, and each one had already been downloaded thousands – or even tens of thousands – of times.

When we analyzed them, we caught two different methods the attackers were using to spread their malware:

• An archive containing the executable wallpaper alongside the malicious files. This payload usually consisted of compromised EXE files, DLLs, or malicious scripts.
• In other cases, attackers threw a curveball by hiding the malware inside a password-protected archive. Either the victim was tricked into typing the password, or a script handled it automatically. The attackers would hide the password in plain sight – either right in the archive’s name or inside a JSON configuration installed along with other wallpaper files. For all the other variations, the payload triggered automatically when the user selected and applied the wallpaper.

Inside an infected game wallpaper

Main screen of the wallpaper application

On the surface, this wallpaper sample (above) we uncovered in December 2025 looks completely harmless. Once launched, there’s absolutely nothing to trigger your suspicion. The built-in game boots up flawlessly, runs smoothly, and the desktop controls work exactly as they should. But behind the scenes, a full-blown infection is underway. Within just a few minutes, a user might suddenly realize their Steam account has been hijacked, or find their computer crippled by malware, with their files being encrypted by ransomware or their system performance tanking because of a hidden crypto miner.

How the malware deploys

Once the game wallpaper launches, it drops a backdoor file called Synaptics.exe (part of the DarkKomet malware family) straight into the victim’s system. At the same time, an executable named ._cache_GAME1.exe fires up to boot the actual game, NTRaholic.

But that ._cache_GAME1.exe module is doing double duty. It simultaneously installs a custom version of a system library called AggregatorHost.dll with a payload inside. This modified library has one main objective: track down the Steam app on the computer and hunt for account credentials.

Looking for the Steam app

Next, the modified library hijacks the user’s live Steam session.

Hijacking the Steam session

After that, the compromised AggregatorHost.dll sends all the collected data to a server controlled by the hackers at hxxp://120.48.156[.]17/ey.php. Once the attackers have control of that active session, they can use the victim’s account to upload even more malicious wallpapers to Steam Workshop.

Attribution and victims

The game wallpaper described above is just one flavor of the many variations we uncovered during our research. By weaponizing the application wallpaper feature, bad actors have successfully distributed almost every type of malware under the sun – from popular infostealers and backdoors to crypto miners and botnet loaders.

Because the range of tools being used is so diverse, we suspect this isn’t the work of a single mastermind. Instead, it looks like multiple scattered, independent hacking groups are all jumping on the same trend. Right now, the primary targets are gamers in China. The wallpaper art styles and titles are tailored specifically to them, and the data backs it up: our security systems caught a staggering 89% of the malicious download attempts happening right there. That said, there’s absolutely nothing stopping these attackers from pivoting and launching a similar campaign in any other part of the world. Russia comes in second place for total downloads at 5.5%, followed by a smattering of other countries and territories: Singapore (1.4%), Hong Kong (0.9%), Germany (0.9%), Vietnam (0.9%), India (0.5%), and Canada (0.5%).

Malicious app wallpaper downloads by region

How to stay safe

Our investigation proves that even trusted platforms like the Steam Workshop aren’t completely safe from malware. In most cases, we caught old, familiar threats such as DarkKomet, the Lumma and Vidar infostealers, and the RenEngine loader. Kaspersky solutions can easily spot and block all of these payloads, no matter how clever the packaging is, thanks to our proactive security layers. Here are some of the specific threat detection verdicts assigned to the objects we discovered during our research:

• HEUR:Trojan-PSW.Win32.gen
• HEUR:Trojan-PSW.Win32.Python.gen
• HEUR:Backdoor.Win32.DarkKomet
• Trojan-Dropper.Python.Agent
• HEUR:Trojan-Ransom.Win32.Gen.gen
• PDM:Trojan.Win32.Generic.

By the time this post went live, the Steam team had already scrubbed the identified malicious wallpapers and links from the platform. However, given how frequently new infected wallpapers keep popping up on the Steam Workshop, you shouldn’t rely on Steam to catch everything. It’s highly recommended to run an antivirus scan on these types of wallpapers before you actually apply them.

Indicators of compromise

MD5

• 95856f2ce428c728d9781d3296558068
• af080780cca2acd1d082ce01e7cc346a
• c133c3dd9f7d6934598025047df41abf
• d1693bbff456ae8fa3360446706df6da
• 8c2cc585ad8a13a72a704c0fda0c9854
• b9fa763a53da3eea742d0f3c845a8c09
• ded08ae5df7f1b12e5fdb767dbbed0b1
• 20965254e29104986e11939decd39549
• 18dedc0009f0927cba6425c84cce9883
• 0f4f01c6d495abb37403072dd017ce8d
• 5620f01284329f561b1839a36be55355
• fe1f6485013cd5e6d5cf718049b0b8d6
• 74414ed4b63aadec039b603c32762b80

C2 servers

• http://202.144.192[.]29
• http://202.144.192[.]29/audit.php
• http://202.144.192[.]29/download2/Themes2.zip
• http://120.48.156[.]17
• http://120.48.156[.]17/ey.php?ka=user1&id
• http://brightly[.]to
• http://brightly[.]to/download2/Themes2.zip
• https://www.dropbox[.]com/s/zhp1b06imehwylq/Synaptics.rar?dl=1
• https://docs.google[.]com/uc?id=0BxsMXGfPIZfSVzUyaHFYVkQxeFk&export=download

Malicious wallpapers

• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3603213159
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3591930233
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3584318845
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3436875036
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3633494498
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3556591375
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3635875825
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3601924072
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3605588743
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3553253793
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3462675635
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3605621824
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3610240788
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3610366547

Update, June 17

We have since confirmed that the malicious wallpapers were present in the app as early as August 2025.

Since late 2025, malware has been spreading rapidly through the Steam Workshop, the gaming platform’s built-in service for players to create and share custom content. The attackers are primarily targeting gamers in China and Russia, aiming to hijack their accounts. To pull this off, they are exploiting Wallpaper Engine – a popular live wallpaper app available on Steam – specifically leveraging its Workshop sharing feature. The malware is hidden inside the wallpaper packages users share with one another. Running one of these compromised wallpapers can lead to a stolen Steam account or leave the victim’s system infected with backdoors or crypto miners.

What is Wallpaper Engine?

Wallpaper Engine is an app that allows you to put animated wallpapers on your desktop. It’s available for both Windows and Android, though our investigation focused strictly on the Windows version. Thanks to a massive Steam community, the app is quite popular, boasting around 100,000 daily active users and nearly a million reviews. It comes with a built-in editor so users can create their own designs, and it supports a few different wallpaper types:

• Videos: MP4, WebM, and other common video formats
• Scenes: interactive wallpapers built inside the app’s own editor
• Web pages: HTML pages powered by JavaScript and CSS, which can also include audio and video elements
• Applications: active windows from third-party Windows-compatible software that Wallpaper Engine sets as the user’s desktop background

That last type, application wallpapers, is where things get risky, because these are essentially standalone programs. They can be anything from mini-games you play right on your desktop, to planners, calendars, system monitors, or widgets tracking your CPU or GPU usage.

Application wallpapers: a built-in security risk

The whole concept of “application wallpapers” essentially allows foreign code to be run directly on your computer. Cybercriminals took note of this feature and started embedding malware right into these types of wallpapers. Because Wallpaper Engine relies on Steam Workshop for content sharing, anyone can create a wallpaper and publish it for the community to download and install for free. Naturally, this setup is a magnet for bad actors.

We discovered dozens of these malicious application wallpapers floating around Steam Workshop, and each one had already been downloaded thousands – or even tens of thousands – of times.

When we analyzed them, we caught two different methods the attackers were using to spread their malware:

• An archive containing the executable wallpaper alongside the malicious files. This payload usually consisted of compromised EXE files, DLLs, or malicious scripts.
• In other cases, attackers threw a curveball by hiding the malware inside a password-protected archive. Either the victim was tricked into typing the password, or a script handled it automatically. The attackers would hide the password in plain sight – either right in the archive’s name or inside a JSON configuration installed along with other wallpaper files. For all the other variations, the payload triggered automatically when the user selected and applied the wallpaper.

Inside an infected game wallpaper

Main screen of the wallpaper application

On the surface, this wallpaper sample (above) we uncovered in December 2025 looks completely harmless. Once launched, there’s absolutely nothing to trigger your suspicion. The built-in game boots up flawlessly, runs smoothly, and the desktop controls work exactly as they should. But behind the scenes, a full-blown infection is underway. Within just a few minutes, a user might suddenly realize their Steam account has been hijacked, or find their computer crippled by malware, with their files being encrypted by ransomware or their system performance tanking because of a hidden crypto miner.

How the malware deploys

Once the game wallpaper launches, it drops a backdoor file called Synaptics.exe (part of the DarkKomet malware family) straight into the victim’s system. At the same time, an executable named ._cache_GAME1.exe fires up to boot the actual game, NTRaholic.

But that ._cache_GAME1.exe module is doing double duty. It simultaneously installs a custom version of a system library called AggregatorHost.dll with a payload inside. This modified library has one main objective: track down the Steam app on the computer and hunt for account credentials.

Looking for the Steam app

Next, the modified library hijacks the user’s live Steam session.

Hijacking the Steam session

After that, the compromised AggregatorHost.dll sends all the collected data to a server controlled by the hackers at hxxp://120.48.156[.]17/ey.php. Once the attackers have control of that active session, they can use the victim’s account to upload even more malicious wallpapers to Steam Workshop.

Attribution and victims

The game wallpaper described above is just one flavor of the many variations we uncovered during our research. By weaponizing the application wallpaper feature, bad actors have successfully distributed almost every type of malware under the sun – from popular infostealers and backdoors to crypto miners and botnet loaders.

Because the range of tools being used is so diverse, we suspect this isn’t the work of a single mastermind. Instead, it looks like multiple scattered, independent hacking groups are all jumping on the same trend. Right now, the primary targets are gamers in China. The wallpaper art styles and titles are tailored specifically to them, and the data backs it up: our security systems caught a staggering 89% of the malicious download attempts happening right there. That said, there’s absolutely nothing stopping these attackers from pivoting and launching a similar campaign in any other part of the world. Russia comes in second place for total downloads at 5.5%, followed by a smattering of other countries and territories: Singapore (1.4%), Hong Kong (0.9%), Germany (0.9%), Vietnam (0.9%), India (0.5%), and Canada (0.5%).

Malicious app wallpaper downloads by region

How to stay safe

Our investigation proves that even trusted platforms like the Steam Workshop aren’t completely safe from malware. In most cases, we caught old, familiar threats such as DarkKomet, the Lumma and Vidar infostealers, and the RenEngine loader. Kaspersky solutions can easily spot and block all of these payloads, no matter how clever the packaging is, thanks to our proactive security layers. Here are some of the specific threat detection verdicts assigned to the objects we discovered during our research:

• HEUR:Trojan-PSW.Win32.gen
• HEUR:Trojan-PSW.Win32.Python.gen
• HEUR:Backdoor.Win32.DarkKomet
• Trojan-Dropper.Python.Agent
• HEUR:Trojan-Ransom.Win32.Gen.gen
• PDM:Trojan.Win32.Generic.

By the time this post went live, the Steam team had already scrubbed the identified malicious wallpapers and links from the platform. However, given how frequently new infected wallpapers keep popping up on the Steam Workshop, you shouldn’t rely on Steam to catch everything. It’s highly recommended to run an antivirus scan on these types of wallpapers before you actually apply them.

Indicators of compromise

MD5

• 95856f2ce428c728d9781d3296558068
• af080780cca2acd1d082ce01e7cc346a
• c133c3dd9f7d6934598025047df41abf
• d1693bbff456ae8fa3360446706df6da
• 8c2cc585ad8a13a72a704c0fda0c9854
• b9fa763a53da3eea742d0f3c845a8c09
• ded08ae5df7f1b12e5fdb767dbbed0b1
• 20965254e29104986e11939decd39549
• 18dedc0009f0927cba6425c84cce9883
• 0f4f01c6d495abb37403072dd017ce8d
• 5620f01284329f561b1839a36be55355
• fe1f6485013cd5e6d5cf718049b0b8d6
• 74414ed4b63aadec039b603c32762b80

C2 servers

• http://202.144.192[.]29
• http://202.144.192[.]29/audit.php
• http://202.144.192[.]29/download2/Themes2.zip
• http://120.48.156[.]17
• http://120.48.156[.]17/ey.php?ka=user1&id
• http://brightly[.]to
• http://brightly[.]to/download2/Themes2.zip
• https://www.dropbox[.]com/s/zhp1b06imehwylq/Synaptics.rar?dl=1
• https://docs.google[.]com/uc?id=0BxsMXGfPIZfSVzUyaHFYVkQxeFk&export=download

Malicious wallpapers

• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3603213159
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3591930233
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3584318845
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3436875036
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3633494498
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3556591375
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3635875825
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3601924072
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3605588743
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3553253793
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3462675635
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3605621824
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3610240788
• https://steamcommunity[.]com/sharedfiles/filedetails/?id=3610366547

Update, June 17

We have since confirmed that the malicious wallpapers were present in the app as early as August 2025.

During our recent threat hunting activities, we found EtherRAT malware being distributed by a website with a strange homepage. This homepage allowed us to discover a vast malicious infrastructure distributing malware, malicious documents, remote desktop software, and phishing pages. 

EtherRAT is a RAT developed in Node.js which allows an attacker to gain complete control over the machine and execute arbitrary code returned by the Command and Control (C2) server. The malware uses the Etherium blockchain to obtain the C2 server, hence the “Ether” part of the name. EtherRAT is typically distributed via MSI, PowerShell, or JavaScript scripts. 

An open directory that distributes EtherRAT: where it all began 

While threat hunting, we found an open directory that was distributing MSI installers and PowerShell scripts, which ultimately distributed EtherRAT. In the analyzed cases, the PowerShell scripts and MSI installers were distributed from a “/install” folder.  The versions have a progressive number, ranging from v1 to v10. 

The returned home page caught our attention and prompted us to further explore the campaign. 

Analyzing domains and associated IPs with the EtherRAT distribution, we detected other similar home pages with a hacking-style theme. They appeared to belong to a larger distribution chain, which also distributes phishing, remote control software, and other malware. These websites usually have several folders with malware and phishing related content, and what is displayed depends on the specific infection chain. 

Different websites that resolve to the same IP addresses have previously returned pages related to fake companies or default templates. The use of these new pages could therefore be a method to make detection more difficult for automated scanners or researchers.  Here are some of the home pages we found:

EtherRAT is an interesting RAT, as it has few lines of code and allows the execution of arbitrary code returned by the C2 server. Furthermore, using the Ethereum blockchain to obtain the C2 server makes it more resilient to infrastructure takedowns. 

Technical analysis of EtherRAT 

The detected websites usually distribute an MSI or PowerShell script with the version name, such as v1.msi, v2.ps1, and so on. 

MSI Loader 

The MSI file “v9.msi” contains three components: 

When the MSI is executed, the “KmPuGimn.cmd” file is started: 

conhost --headless cmd /c "KmPuGimn.cmd" 

This obfuscated BAT file performs different operations: 

• Extracts the other files in a random folder in %LOCALAPPDATA%. 
• Re-executes itself via: 
  • %SystemRoot%\System32\conhost.exe –headless %SystemRoot%\System32\cmd.exe /c call “C:\Users\{user}\AppData\Local\{random_path}\KmPuGimn.cmd” nKWa 
• Runs the command “where node” to find an existing installation. 
• Downloads Node.js if it’s not found 
  • Uses “curl -sLo” to download Node.js from the official website. 
  • Extracts to installation directory via “tar -xf”. 
  • Renames extracted directory to “28Q75h”.
• Loops until both “MRaQCipBIZeiZNx.log” and “cDQMlQAru0.xml” exist, then executes: 
  • conhost.exe –headless C:\Users\{user}\AppData\Local\{random_path}\{random_path}\node.exe cDQMlQAru0.xml 

The executed “cDQMlQAru0.xml” is a loader that decrypts the embedded code with a XOR function and then executes it with “vm.compileFunction”. 

decrypted[i] = (encrypted[i] - key[i % key.length] - i) & 0xFF 

The decrypted code: 

• Copies node.exe in “C:\Users\{user}\AppData\Local\{random_path}\{random_path}\_MJlLlt5.exe”. 
• Adds a registry key for persistence with “conhost.exe –headless”. 
• Decrypts “MRaQCipBIZeiZNx.log” and executes it with “_MJlLlt5.exe” stdin. 

The decryption algorithm is a custom stream-like decoding routing based on XOR, byte rotations and an accumulator: 

for e in range(len(data)): 
    byte = data[e] 
    g = prev 
    prev = byte 
    byte = (byte - g) & 0xff 
    byte = byte ^ n[e % len(n)] ^ ((e >> 8) & 0xff) 
    byte = si[byte] 
    byte = (byte - k[e % len(k)]) & 0xff
    result[e] = byte 

The final stage is to deploy EtherRAT. EtherRAT allows the attacker to: 

• Execute arbitrary JavaScript code received by the C2 server. This allows the attacker to execute new commands, perform operations on files and folders, modify the registry, and exfiltrate data. 
• Get a new C2 server using the Ethereum blockchain. 
• Reobfuscate itself. 
• Save the logs to “svchost.log”. 

The EtherRAT uses Ethereum’s “eth_call” JSON-RPC method to retrieve the active C2 URL from a smart contract on the Ethereum mainnet.  

The blockchain parameters in this case are: 

• Contract: 0x88ea8d0bc4146f0a018e989df3fd089ac48f9a58 
• Function selector: 0x7d434425 
• Argument: 0xf6a772e163e64b07f658946f863b5d457d88f9f0 

The contacted URLs to obtain the C2 server endpoint are: 

• mainnet[.]gateway[.]tenderly[.]co 
• rpc[.]flashbots[.]net/fast 
• rpc[.]mevblocker[.]io 
• eth-mainnet[.]public[.]blastapi[.]io 
• ethereum-rpc[.]publicnode[.]com 
• eth[.]drpc[.]org 
• eth[.]merkle[.]io 

Polling requests use randomized URL patterns based on some parameters defined in the code: 

GET /api/<4-byte-hex>/<victim-uuid>/<4-byte-hex>.<ext>?<param>=<build-id> 
X-Bot-Server: <c2_url> 

In the analyzed sample, the parameters are: 

• Build ID: “6f816d80-0d6c-4384-9cd6-6b79965fc08f” 
• ext: randomly selected from “png”, “jpg”, “gif”, “css”, “ico”, “webp”. 
• param: randomly selected from “id”, “token”, “key”, “b”, “q”, “s”, “v”. 

After startup, the RAT sends its own source code to the C2 server. The C2 responds with a newly obfuscated version of the script, which is written back to disk, making each execution generate a new file hash. 

POST /api/[REOBF_PATH]/<victim-uuid> 
Body: { "code": "<current_script_contents>", "build": "<build_id>" } 

After the EtherRAT execution, we observed different post-compromised cmd.exe activities to check the environment. For example: 

• powershell -NoProfile -NonInteractive -WindowStyle Hidden -Command “(Get-WmiObject Win32_VideoController).Name”
• reg query “HKLM\SOFTWARE\Microsoft\Cryptography” /v MachineGuid 
• powershell -NoProfile -NonInteractive -WindowStyle Hidden -Command “(Get-WmiObject Win32_ComputerSystem).Domain” 
• powershell -NoProfile -NonInteractive -WindowStyle Hidden -Command “(Get-WmiObject Win32_ComputerSystem).PartOfDomain” 
• cmd.exe /d /s /c “net session” 

PowerShell Loader 

The activities performed by the PowerShell loaders are very similar to the last stage of the JS script of the MSI installer: 

• Downloads Node.js if it’s not present. 
• Create the necessary directories. 
• Decode the EtherRAT with a custom decryption algorithm. 
• Execute Node.js with conhost.exe and the decrypted EtherRAT payload. 

We detected some variants of the PowerShell loader hosted on these websites; namely that the functions’ names and the decryption functions change in the analyzed PowerShell scripts. 

Tracking the malicious infrastructure 

When we analyzed the different websites with the “hacking-theme” pages, we found that in the past many had hosted multiple phishing pages in some specific paths. For example: 

• /zht/sharep-redirect.html 
• /bl/me.php 
• /t/teams 
• /teams/Windows/invite.php 

It seems that these domains and IPs are actually part of a much larger infrastructure that distributes malware, phishing, malicious documents, and remote software. It is possible that these infrastructures are shared by multiple threat actors who activate different URL endpoints based on the specific campaign. 

Interestingly, the majority of the domains related to this malicious infrastructure in the past also returned an HTML page related to a “Bulletproof Infrastructure” service.  

We found that these phishing campaigns typically start via emails with documents attached, such as PDF or Excel files. These documents ask the user to click a link to view another document. Below are two examples of the phishing documents attached to the emails:

These phishing pages typically ask the user to enter their email address, then continue the infection chain and distribute phishing or malware pages.  Below are some of the phishing pages detected within the malicious infrastructure:

Misconfigurations exposed the phishing kits 

While tracking malicious websites, we found one with an open directory containing part of the phishing kit used in the campaigns. 

The open directory contained several folders with code and pages related to the phishing campaigns. 

Additionally, some domains were misconfigured and allowed the download of “cl.zip”, which contained the source code for the “URL Cloaker” pages. 

Indicators of Compromise (IOCs)  

IPs 

82[.]165[.]65[.]244: malicious infrastructure  

185[.]221[.]216[.]121: malicious infrastructure  

43[.]163[.]233[.]166: malicious infrastructure  

40[.]160[.]238[.]30: malicious infrastructure  

159[.]89[.]227[.]204: malicious infrastructure  

57[.]128[.]31[.]168: malicious infrastructure  

Domains 

ivorilla[.]cloud: EtherRAT distribution  

mx[.]nrlwz[.]com: EtherRAT distribution  

dn[.]eyqwj[.]com: EtherRAT distribution  

bi[.]mkrjcsw[.]com: EtherRAT distribution  

dorqen[.]casa: EtherRAT distribution  

kelvra[.]club: EtherRAT distribution  

cambioefectivo[.]com: EtherRAT C2  

vabelles[.]com: EtherRAT C2  

tranzed[.]org: EtherRAT C2  

kibrisarazi[.]com: EtherRAT C2  

aravisblog[.]com: EtherRAT C2  

publicspeakingtip[.]org: EtherRAT C2  

Acknowledgements 

• EtherRAT: https://atos.net/en/lp/cybershield/etherrat-distribution-spoofing-administrative-tools-via-github-facades 

• SharePoint reference: https://ironscales.com/threat-intelligence/no-macro-xlsx-shared-strings-aitm-redirect-credential-harvest 

Stop threats before they can do any harm.

Malwarebytes Browser Guard blocks phishing pages and malicious sites automatically. Free, one click to install. Add it to your browser →

During our recent threat hunting activities, we found EtherRAT malware being distributed by a website with a strange homepage. This homepage allowed us to discover a vast malicious infrastructure distributing malware, malicious documents, remote desktop software, and phishing pages. 

EtherRAT is a RAT developed in Node.js which allows an attacker to gain complete control over the machine and execute arbitrary code returned by the Command and Control (C2) server. The malware uses the Etherium blockchain to obtain the C2 server, hence the “Ether” part of the name. EtherRAT is typically distributed via MSI, PowerShell, or JavaScript scripts. 

An open directory that distributes EtherRAT: where it all began 

While threat hunting, we found an open directory that was distributing MSI installers and PowerShell scripts, which ultimately distributed EtherRAT. In the analyzed cases, the PowerShell scripts and MSI installers were distributed from a “/install” folder.  The versions have a progressive number, ranging from v1 to v10. 

The returned home page caught our attention and prompted us to further explore the campaign. 

Analyzing domains and associated IPs with the EtherRAT distribution, we detected other similar home pages with a hacking-style theme. They appeared to belong to a larger distribution chain, which also distributes phishing, remote control software, and other malware. These websites usually have several folders with malware and phishing related content, and what is displayed depends on the specific infection chain. 

Different websites that resolve to the same IP addresses have previously returned pages related to fake companies or default templates. The use of these new pages could therefore be a method to make detection more difficult for automated scanners or researchers.  Here are some of the home pages we found:

EtherRAT is an interesting RAT, as it has few lines of code and allows the execution of arbitrary code returned by the C2 server. Furthermore, using the Ethereum blockchain to obtain the C2 server makes it more resilient to infrastructure takedowns. 

Technical analysis of EtherRAT 

The detected websites usually distribute an MSI or PowerShell script with the version name, such as v1.msi, v2.ps1, and so on. 

MSI Loader 

The MSI file “v9.msi” contains three components: 

When the MSI is executed, the “KmPuGimn.cmd” file is started: 

conhost --headless cmd /c "KmPuGimn.cmd" 

This obfuscated BAT file performs different operations: 

• Extracts the other files in a random folder in %LOCALAPPDATA%. 
• Re-executes itself via: 
  • %SystemRoot%\System32\conhost.exe –headless %SystemRoot%\System32\cmd.exe /c call “C:\Users\{user}\AppData\Local\{random_path}\KmPuGimn.cmd” nKWa 
• Runs the command “where node” to find an existing installation. 
• Downloads Node.js if it’s not found 
  • Uses “curl -sLo” to download Node.js from the official website. 
  • Extracts to installation directory via “tar -xf”. 
  • Renames extracted directory to “28Q75h”.
• Loops until both “MRaQCipBIZeiZNx.log” and “cDQMlQAru0.xml” exist, then executes: 
  • conhost.exe –headless C:\Users\{user}\AppData\Local\{random_path}\{random_path}\node.exe cDQMlQAru0.xml 

The executed “cDQMlQAru0.xml” is a loader that decrypts the embedded code with a XOR function and then executes it with “vm.compileFunction”. 

decrypted[i] = (encrypted[i] - key[i % key.length] - i) & 0xFF 

The decrypted code: 

• Copies node.exe in “C:\Users\{user}\AppData\Local\{random_path}\{random_path}\_MJlLlt5.exe”. 
• Adds a registry key for persistence with “conhost.exe –headless”. 
• Decrypts “MRaQCipBIZeiZNx.log” and executes it with “_MJlLlt5.exe” stdin. 

The decryption algorithm is a custom stream-like decoding routing based on XOR, byte rotations and an accumulator: 

for e in range(len(data)): 
    byte = data[e] 
    g = prev 
    prev = byte 
    byte = (byte - g) & 0xff 
    byte = byte ^ n[e % len(n)] ^ ((e >> 8) & 0xff) 
    byte = si[byte] 
    byte = (byte - k[e % len(k)]) & 0xff
    result[e] = byte 

The final stage is to deploy EtherRAT. EtherRAT allows the attacker to: 

• Execute arbitrary JavaScript code received by the C2 server. This allows the attacker to execute new commands, perform operations on files and folders, modify the registry, and exfiltrate data. 
• Get a new C2 server using the Ethereum blockchain. 
• Reobfuscate itself. 
• Save the logs to “svchost.log”. 

The EtherRAT uses Ethereum’s “eth_call” JSON-RPC method to retrieve the active C2 URL from a smart contract on the Ethereum mainnet.  

The blockchain parameters in this case are: 

• Contract: 0x88ea8d0bc4146f0a018e989df3fd089ac48f9a58 
• Function selector: 0x7d434425 
• Argument: 0xf6a772e163e64b07f658946f863b5d457d88f9f0 

The contacted URLs to obtain the C2 server endpoint are: 

• mainnet[.]gateway[.]tenderly[.]co 
• rpc[.]flashbots[.]net/fast 
• rpc[.]mevblocker[.]io 
• eth-mainnet[.]public[.]blastapi[.]io 
• ethereum-rpc[.]publicnode[.]com 
• eth[.]drpc[.]org 
• eth[.]merkle[.]io 

Polling requests use randomized URL patterns based on some parameters defined in the code: 

GET /api/<4-byte-hex>/<victim-uuid>/<4-byte-hex>.<ext>?<param>=<build-id> 
X-Bot-Server: <c2_url> 

In the analyzed sample, the parameters are: 

• Build ID: “6f816d80-0d6c-4384-9cd6-6b79965fc08f” 
• ext: randomly selected from “png”, “jpg”, “gif”, “css”, “ico”, “webp”. 
• param: randomly selected from “id”, “token”, “key”, “b”, “q”, “s”, “v”. 

After startup, the RAT sends its own source code to the C2 server. The C2 responds with a newly obfuscated version of the script, which is written back to disk, making each execution generate a new file hash. 

POST /api/[REOBF_PATH]/<victim-uuid> 
Body: { "code": "<current_script_contents>", "build": "<build_id>" } 

After the EtherRAT execution, we observed different post-compromised cmd.exe activities to check the environment. For example: 

• powershell -NoProfile -NonInteractive -WindowStyle Hidden -Command “(Get-WmiObject Win32_VideoController).Name”
• reg query “HKLM\SOFTWARE\Microsoft\Cryptography” /v MachineGuid 
• powershell -NoProfile -NonInteractive -WindowStyle Hidden -Command “(Get-WmiObject Win32_ComputerSystem).Domain” 
• powershell -NoProfile -NonInteractive -WindowStyle Hidden -Command “(Get-WmiObject Win32_ComputerSystem).PartOfDomain” 
• cmd.exe /d /s /c “net session” 

PowerShell Loader 

The activities performed by the PowerShell loaders are very similar to the last stage of the JS script of the MSI installer: 

• Downloads Node.js if it’s not present. 
• Create the necessary directories. 
• Decode the EtherRAT with a custom decryption algorithm. 
• Execute Node.js with conhost.exe and the decrypted EtherRAT payload. 

We detected some variants of the PowerShell loader hosted on these websites; namely that the functions’ names and the decryption functions change in the analyzed PowerShell scripts. 

Tracking the malicious infrastructure 

When we analyzed the different websites with the “hacking-theme” pages, we found that in the past many had hosted multiple phishing pages in some specific paths. For example: 

• /zht/sharep-redirect.html 
• /bl/me.php 
• /t/teams 
• /teams/Windows/invite.php 

It seems that these domains and IPs are actually part of a much larger infrastructure that distributes malware, phishing, malicious documents, and remote software. It is possible that these infrastructures are shared by multiple threat actors who activate different URL endpoints based on the specific campaign. 

Interestingly, the majority of the domains related to this malicious infrastructure in the past also returned an HTML page related to a “Bulletproof Infrastructure” service.  

We found that these phishing campaigns typically start via emails with documents attached, such as PDF or Excel files. These documents ask the user to click a link to view another document. Below are two examples of the phishing documents attached to the emails:

These phishing pages typically ask the user to enter their email address, then continue the infection chain and distribute phishing or malware pages.  Below are some of the phishing pages detected within the malicious infrastructure:

Misconfigurations exposed the phishing kits 

While tracking malicious websites, we found one with an open directory containing part of the phishing kit used in the campaigns. 

The open directory contained several folders with code and pages related to the phishing campaigns. 

Additionally, some domains were misconfigured and allowed the download of “cl.zip”, which contained the source code for the “URL Cloaker” pages. 

Indicators of Compromise (IOCs)  

IPs 

82[.]165[.]65[.]244: malicious infrastructure  

185[.]221[.]216[.]121: malicious infrastructure  

43[.]163[.]233[.]166: malicious infrastructure  

40[.]160[.]238[.]30: malicious infrastructure  

159[.]89[.]227[.]204: malicious infrastructure  

57[.]128[.]31[.]168: malicious infrastructure  

Domains 

ivorilla[.]cloud: EtherRAT distribution  

mx[.]nrlwz[.]com: EtherRAT distribution  

dn[.]eyqwj[.]com: EtherRAT distribution  

bi[.]mkrjcsw[.]com: EtherRAT distribution  

dorqen[.]casa: EtherRAT distribution  

kelvra[.]club: EtherRAT distribution  

cambioefectivo[.]com: EtherRAT C2  

vabelles[.]com: EtherRAT C2  

tranzed[.]org: EtherRAT C2  

kibrisarazi[.]com: EtherRAT C2  

aravisblog[.]com: EtherRAT C2  

publicspeakingtip[.]org: EtherRAT C2  

Acknowledgements 

• EtherRAT: https://atos.net/en/lp/cybershield/etherrat-distribution-spoofing-administrative-tools-via-github-facades 

• SharePoint reference: https://ironscales.com/threat-intelligence/no-macro-xlsx-shared-strings-aitm-redirect-credential-harvest 

Stop threats before they can do any harm.

Malwarebytes Browser Guard blocks phishing pages and malicious sites automatically. Free, one click to install. Add it to your browser →

Protect enterprise AI agents from supply chain risks by auditing third-party skills for hidden vulnerabilities and multi-stage attack chains.

The post Trust No Skill: Integrity Verification for AI Agent Supply Chains appeared first on Unit 42.

Blogs

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Identity Is the New Attack Surface: How Infostealers Are Reshaping Enterprise Risk

Our new guide explores how infostealers are fueling modern identity-based attacks and how organizations can build a proactive defense before stolen access is weaponized.

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Flashpoint

June 10, 2026

Table Of Contents

Table of Contents

The New Reality of Identity-Based Threats

Why Identity Has Become the Preferred Attack Surface

What Is an Identity-Based Attack?

From Credential Theft to Identity Exploitation

Turning Exposure Into Actionable Intelligence

Building a Proactive Defense Across the Identity Layer

Key Infostealer Statistics

Frequently Asked Questions (FAQ)

More

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The New Reality of Identity-Based Threats

A publicly exposed database surfaced in early 2026 containing more than 149 million stolen login credentials. The records were not tied to a single breach or organization. Instead, they had been quietly collected over time from devices infected with information-stealing malware, with each record containing usernames, passwords, session data, and the context needed to use them.

Unlike traditional breach dumps, this data was structured, searchable, and immediately actionable. Credentials were mapped to specific services, session artifacts reflected active logins, and much of the information was recent enough to enable direct access without triggering traditional security controls.

This incident reflects a broader shift in the threat landscape.

More than 11.1 million devices were infected with infostealers last year, fueling a supply of over 3.3 billion stolen credentials, session cookies, cloud tokens, and other forms of identity data now circulating across illicit markets.

For security teams, the challenge is no longer simply detecting a breach after it occurs. It is understanding when access may already exist — where compromised credentials are circulating, how they are being used, and how quickly they can be weaponized.

That’s why Flashpoint created Identity Is the New Attack Surface: A Guide to Infostealers and Proactive Defense.

Drawing on Flashpoint’s Primary Source Collection (PSC) and analyst-driven intelligence, this guide helps IT, Threat Intelligence, Fraud, and HUNT teams understand how infostealers operate, how stolen identity data fuels real-world attacks, and how organizations can move from reactive response to proactive defense.

The guide explores:

• How today’s most active infostealers power modern attack chains
• How threat actors weaponize stolen credentials, cookies, and session data
• How organizations can operationalize infostealer intelligence for proactive defense
• How to evaluate infostealer intelligence providers and detection capabilities

Report

Identity Is the New Attack Surface: A Guide to Infostealers and Proactive Defense

Download this guide to learn how to build an infostealer defense program, with Flashpoint’s proprietary data …

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Why Identity Has Become the Preferred Attack Surface

For years, security teams focused on vulnerabilities, malware delivery, and network intrusion as the primary paths to compromise. Increasingly, however, threat actors are taking a different

Modern infostealers such as Lumma, StealC, Vidar, Acreed, and Rhadamanthys provide attackers with something more valuable than initial access: usable identity. These malware families collect credentials, browser artifacts, session cookies, application data, and host metadata that help threat actors understand how a victim authenticates and what systems they can access.

A single infected device can expose credentials, browser artifacts, session cookies, application data, host metadata, and access to enterprise SaaS platforms. Together, these artifacts create a detailed profile of how a user authenticates, what systems they access, and how those systems trust that identity.

This is what makes infostealer data so valuable.

“For years, organizations have invested heavily in detecting malware, blocking exploits, and hardening infrastructure. Meanwhile, attackers have increasingly shifted to a simpler strategy: logging in with valid identities.

Infostealers have fundamentally changed the economics of access. Threat actors no longer need to compromise a network directly when billions of credentials, session cookies, and authentication artifacts are already circulating in underground ecosystems. The challenge for defenders has risen from preventing compromise to identifying where access already exists and how quickly it can be weaponized.”

Ian Gray, Vice President of Intelligence at Flashpoint

Identity data is inherently reusable. A stolen credential can be tested across multiple services. A session cookie can potentially allow attackers to hijack authenticated sessions. Browser and host metadata can help threat actors recreate a victim’s environment and bypass security controls designed to detect suspicious logins.

What begins as a single infection can quickly evolve into access across multiple systems, applications, and organizations.

What Is an Identity-Based Attack?

Identity-based attacks occur when threat actors use legitimate credentials, session cookies, authentication tokens, or other identity artifacts to gain access to systems and applications. Rather than exploiting a vulnerability or deploying malware inside a target environment, attackers authenticate as trusted users using stolen identity data.

This shift is one of the primary reasons infostealers have become so valuable. Modern infostealer logs often contain far more than usernames and passwords. They may also include browser cookies, session information, host metadata, application data, and other artifacts that help attackers understand how a user authenticates and what systems they can access. When combined, this information enables account takeover, fraud, lateral movement, and other forms of identity-based abuse.

From Credential Theft to Identity Exploitation

The way threat actors operationalize stolen data is evolving just as rapidly as the data itself.

Historically, attackers often had to manually review stolen credentials and determine which accounts were worth pursuing. Today, that process is increasingly automated.

Infostealer logs can be aggregated, tested, and prioritized at scale, allowing threat actors to rapidly identify valid access across enterprise systems, SaaS platforms, VPNs, and cloud environments.

Flashpoint identifies this as a hybrid threat: the convergence of large-scale identity compromise and automated exploitation.

Once valid access is identified, attackers can move quickly. Credentials may be reused across services. Session data can be leveraged for account takeover. Access can be sold to ransomware operators, fraud actors, or other criminal groups. In many cases, exposure itself becomes part of the attack lifecycle rather than merely a precursor to it.

The result is a threat landscape where stolen identity data is not simply stored and sold. It is continuously tested, validated, reused, and operationalized.

Turning Exposure Into Actionable Intelligence

For defenders, prevention remains important. But prevention alone is no longer enough.

Organizations must also be able to identify when credentials, session cookies, and other identity artifacts have already been exposed and are circulating within underground ecosystems.

The earliest opportunity to intervene is often after data has been exfiltrated but before attackers have successfully operationalized it.

Achieving that visibility requires more than traditional breach feeds or aggregated datasets.

Flashpoint’s Primary Source Collection approach provides direct visibility into the forums, marketplaces, Telegram channels, malware repositories, and illicit communities where infostealer activity originates. Rather than relying solely on recycled breach data, Flashpoint continuously collects from the environments where stolen identity data is first shared, sold, and operationalized.

However, collection alone is not enough.

Raw infostealer logs are noisy, fragmented, and difficult to operationalize at scale. Flashpoint transforms these logs into structured intelligence through a multi-stage workflow that includes:

• Source ingestion from underground ecosystems
• Normalization and de-duplication of collected data
• Automated parsing and enrichment of credentials, cookies, host metadata, and malware attribution
• Structured output that supports alerts, investigations, and integrations across existing security workflows

This process helps defenders understand not only what was exposed, but who may be affected, how exposure occurred, what systems may be at risk, and how quickly action is required.

Building a Proactive Defense Across the Identity Layer

The rise of infostealers has fundamentally changed how organizations should think about attack surface management.

The attack surface is no longer limited to infrastructure, endpoints, or internet-facing applications. It now includes the digital identities of employees, partners, vendors, and customers.

Security teams need visibility into the identity layer itself — understanding where exposure exists, how attackers are leveraging stolen data, and what actions should be taken before access is exploited.

By combining direct visibility into underground ecosystems with structured, actionable intelligence, organizations can identify compromised accounts earlier, uncover infection trends, prioritize response efforts, and reduce the likelihood of downstream compromise.

Download Identity Is the New Attack Surface: A Guide to Infostealers and Proactive Defense to learn how your organization can build a proactive defense program across the identity layer.

Key Infostealer Statistics

According to Flashpoint research:

• More than 11.1 million devices were infected with infostealers in the last year.
• Over 3.3 billion credentials, session cookies, cloud tokens, and identity artifacts are circulating across illicit markets.
• Flashpoint analysts identified 30+ active infostealer strains being sold across underground ecosystems.
• Flashpoint’s credential database contains 48+ billion credentials, including more than 1 billion tied to infostealer activity.
• More than 4.2% of infostealer-exposed credentials include browser cookies that may support session hijacking.
• Flashpoint can collect and parse some infostealer logs within one to two days of infection.

Frequently Asked Questions (FAQ)

FAQ: Infostealers and Identity-Based Threats

What is an infostealer?

An infostealer is a type of malware designed to collect sensitive information from an infected device. Depending on the strain, this can include usernames and passwords, browser cookies, session tokens, saved payment information, cryptocurrency wallets, system metadata, and other identity-related artifacts.

How do infostealers work?

Infostealers infect a victim’s device and collect information such as credentials, browser data, session cookies, autofill information, cryptocurrency wallet data, and system metadata. The stolen information is packaged into files known as infostealer logs, which can then be sold, shared, or operationalized by threat actors.

What information can infostealers steal?

Depending on the malware family, infostealers can collect usernames and passwords, session cookies, authentication tokens, browser history, saved payment information, cryptocurrency wallet data, system information, installed applications, and other identity-related artifacts. The goal is to provide attackers with enough information to access accounts and impersonate legitimate users.

What are the most common infostealers?

The infostealer ecosystem changes rapidly, but Flashpoint analysts currently track strains such as Lumma (also known as LummaC2/Remus), StealC, Vidar, Acreed, and Rhadamanthys among the most prominent malware families driving credential theft and identity-based attacks.

Why are infostealers so dangerous?

Infostealers provide attackers with more than credentials. Modern infostealer logs often contain the context needed to use stolen data, including session information, browser artifacts, and device metadata. This allows threat actors to perform account takeovers, move laterally within environments, and gain access to business-critical systems. According to Flashpoint’s 2026 Global Threat Intelligence Report, more than 11.1 million devices were infected with infostealers last year, contributing to a pool of over 3.3 billion stolen credentials, session cookies, cloud tokens, and other identity artifacts.

What is an infostealer log?

An infostealer log is a package of data collected from an infected device. Logs may contain credentials, cookies, browser data, application information, host metadata, and other artifacts that help attackers understand how a victim authenticates and what systems they can access.

Can infostealers bypass multi-factor authentication (MFA)?

In some cases, yes. While multifactor authentication remains a critical security control, stolen session cookies and authenticated session data can sometimes allow threat actors to hijack existing sessions without needing to complete the MFA process themselves. Flashpoint found that more than 4.2% of infostealer-exposed credentials in its dataset were associated with browser cookies, highlighting the growing importance of session-based risk.

How do threat actors obtain infostealer logs?

Infostealer logs are frequently bought and sold across illicit marketplaces, forums, Telegram channels, and other underground communities. Many are distributed through Malware-as-a-Service (MaaS) offerings that make infostealer capabilities accessible to a wide range of threat actors. Flashpoint analysts identified more than 30 unique infostealer strains actively offered for sale across underground ecosystems.

How can organizations detect credential exposure from infostealers?

Organizations can monitor underground sources where stolen data is shared and sold, identify exposed credentials associated with their domains, and investigate related artifacts such as cookies, host metadata, and malware attribution. The earlier exposure is identified, the greater the opportunity to remediate before attackers operationalize access. Flashpoint collects and parses some infostealer logs within one to two days of infection, helping organizations detect exposure closer to the point of compromise.

What should organizations do if employee credentials appear in an infostealer log?

Organizations should immediately assess the scope of exposure, reset affected credentials, invalidate active sessions, review authentication activity, investigate the infected device, and determine whether additional accounts or systems may have been impacted.

How is Flashpoint’s approach to infostealer intelligence different from traditional breach monitoring?

Many organizations rely on aggregated breach feeds or credential dumps that may be weeks or months old by the time they are discovered. Flashpoint’s Primary Source Collection (PSC) approach provides direct visibility into the forums, marketplaces, Telegram channels, and underground communities where stolen identity data is first shared, sold, and operationalized.

In addition to collecting raw infostealer logs, Flashpoint parses and enriches the data with context such as malware attribution, session cookies, host metadata, browser artifacts, and affected identities. Today, Flashpoint’s credential database contains more than 48 billion credentials, including over 1 billion tied to infostealer activity, providing organizations with actionable intelligence rather than raw exposure data.

The post Identity Is the New Attack Surface: How Infostealers Are Reshaping Enterprise Risk appeared first on Flashpoint.

Tech company says it ‘caught and disrupted’ NSO Group’s attempts to access accounts in Jordan and Lebanon

A spyware firm has been targeting WhatsApp users with malicious links in contravention of a US court order forbidding it from doing so, Meta has said.

In a post, Meta said WhatsApp had “caught and disrupted spear phishing attempts” by NSO Group, which a spokesperson said targeted a handful of users in Jordan and Lebanon. It had also caught the group creating “test accounts and groups” on WhatsApp.