Microsoft says it dismantled a malware-signing-as-a-service (MSaaS) called Fox Tempest, which helped cybercriminals make malware appear legitimate.
The service let customers submit malicious files to be digitally signed with short-lived Microsoft-issued certificates, making the malware look legitimate and more likely to bypass security checks.
Fox Tempest’s service was built around a customer-facing signing workflow where cybercriminals could upload malicious binaries to a portal, have them signed with certificates valid for only 72 hours, and then receive files that appeared to come from a trusted software source.
Microsoft explicitly says this approach allowed malware to evade security controls and bypass defenses that would otherwise flag suspicious unsigned code. Many security tools treat signed binaries as more trustworthy than unsigned ones, especially in environments that rely on allow-lists and publisher reputation. Fox Tempest abused that assumption by using fraudulently obtained certificates to make malware blend in as legitimate software, increasing the likelihood of execution and successful delivery.
A trusted-looking certificate can help malware get past initial scrutiny, especially when paired with social engineering, paid ads, SEO poisoning, or fake download pages. In this campaign, the signing layer helped malicious installers masquerade as products like AnyDesk, Teams, PuTTY, and Webex, which is exactly the kind of abuse that can slip through control frameworks built around reputation and trust.
The fraudulent certificates were used to spread ransomware and infostealers. The effects of these malware campaigns were broad, with attacks affecting healthcare, education, government, and financial services across multiple countries.
How to stay safe
Microsoft’s disclosure shows how cybercrime has evolved beyond “malware authors” into a service economy where one group specializes in producing trust and others monetize it.
For defenders, the strongest lesson is not to treat code signing as a standalone security control.
For consumers:
Remember to only download software from the official vendor site, the Microsoft Store, or another source you already trust. Avoid download buttons on links sent via social media posts, direct messages or email.
Be skeptical of “sponsored” search results and advertisements for popular apps.
Use an up-to-date, real-time anti-malware solution that looks for malicious behavior rather than just signatures.
We don’t just report on threats—we remove them
Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.
Malicious actors have developed a new way to steal data stored by Chrome for Windows. Researchers discovered the technique while analyzing a fresh build of an infostealer known as VoidStealer. The new method allows the malware to bypass Chrome’s Application-Bound (App-Bound) Encryption (ABE), a mechanism intended to protect session cookies and other valuable information stored in the browser.
Google hoped this mechanism would secure the master key Chrome uses to encrypt all sensitive data. Unfortunately, this isn’t the first time malware authors have found a workaround for this defense — leaving secrets stored in Chrome vulnerable once again.
How App-Bound Encryption works in Chrome
Google introduced App-Bound Encryption in July 2024 with the release of Chrome version 127. The company’s announcement mentioned infostealers snatching cookies from Chrome users on Windows as the primary problem ABE was intended to solve. We’ve already covered in detail what these files are and the consequences of their theft, so we’ll only briefly recap the main facts here.
Cookies are small files that the browser saves to the user’s device at a website’s request to remember various site settings. Of particular value to attackers are session cookies, which are used for automatic authentication on websites. It’s thanks to these files that we don’t have to enter a username and password every time we revisit a site.
But this convenience carries a risk: stealing these files allows an attacker to use an already-authenticated session without entering a username or password. This allows them to impersonate the user, which can lead to account hijacking, theft of personal or financial data, and other adverse consequences.
Infostealer Trojans are particularly dangerous for Chrome users on Windows. This is because, on this OS, Chrome previously relied solely on the standard built-in Data Protection API (DPAPI). With this system encryption mechanism, applications don’t need to create and store encryption keys to protect data.
The limitation of DPAPI is that it doesn’t protect data from malware that’s already successfully compromised the system and is capable of executing code on behalf of the logged-in user. This is exactly what stealers exploit: since they typically run with the user’s privileges, they can simply request DPAPI to decrypt the browser’s protected data.
The ABE mechanism was designed to solve that specific problem. The core idea is right in the name: App-Bound Encryption means the encryption is tied to a specific application. To achieve this, a separate service running with system privileges is responsible for protecting the key used to encrypt Chrome’s data. It verifies which application is requesting access to the key, and denies the request if it doesn’t originate from Chrome.
Chrome’s App-Bound Encryption (ABE) was designed so that only Chrome itself could retrieve the master key needed to decrypt the browser’s stored data. Source
As a result, the architects of this feature assumed that to access ABE-protected browser data, an infostealer would either need to escalate its privileges to system-level, or inject malicious code directly into Chrome. In theory, this should have made attacking Chrome significantly harder and reduced the effectiveness of mass-market infostealers. As you might have guessed, things didn’t go quite that smoothly in practice.
Previous successful bypasses of Chrome’s ABE
Just a couple of months after Google announced the implementation of App-Bound Encryption in Chrome, many infostealer developers claimed they’d already bypassed the protection. Among them were the creators of Meduza Stealer, Whitesnake, Lumma Stealer, and Lumar (also known as PovertyStealer).
Lumma stealer developers announce a bypass for Chrome’s App-Bound Encryption in a new version of the malware
Of course, you shouldn’t take malware developers at their word, but legitimate security researchers were able to confirm at least some of the claims. Bypasses for Google Chrome’s new data protection feature did become available almost immediately after its release.
A month later, in October 2024, tech enthusiast Alex Hagenah published a tool on GitHub called Chrome-App-Bound-Encryption-Decryption to bypass Google’s new security mechanism. Analysis of the tool’s code revealed that its author used roughly the same methods that attackers were already heavily exploiting.
What followed was a game of cat and mouse: security researchers and stealer developers came up with new tricks to circumvent App-Bound Encryption, while Google patched the newly discovered loopholes with varying degrees of success.
VoidStealer — a new data-nabbing menace
This brings us to recent events: in March 2026, news broke about a stealer named VoidStealer, which utilizes a brand-new and, by all accounts, highly effective method for bypassing ABE.
VoidStealer developers advertising a new method for bypassing ABE. Source
The malware authors developed an attack technique that targets the brief moment when the master key sits in the browser’s memory in plaintext. This occurs because, at a certain point, the browser inevitably has to decrypt its data to actually use it — for instance, to automatically sign in to a website with the relevant session cookie or to access saved credentials.
To exploit this window of opportunity, the malware attaches itself to the Chrome process as a debugger — a tool that allows one to control a program’s execution, pause it, and inspect its memory. In legitimate scenarios, these tools are used by developers to find and fix bugs, analyze application behavior, and test performance.
The malware identifies the specific section of code where data decryption takes place. It then sets a breakpoint at that location; when the program’s execution reaches that point, the browser effectively freezes. This is how the malware catches the exact moment the master key is sitting in RAM in plaintext; it then reads the key directly from memory.
It’s worth noting that everything mentioned above also applies to other Chromium-based browsers that use ABE, including Microsoft Edge, Brave, Opera, Vivaldi, and others.
How to avoid falling victim to infostealers
The scale of VoidStealer’s reach could be significant, as its developers operate under the malware-as-a-service (MaaS) model. This means they rent out the ready-made tool to other attackers, so they don’t need to develop custom malware from scratch.
This situation demonstrates that relying solely on built-in security mechanisms isn’t enough. Unfortunately, stealer developers are coming up with new workarounds faster than browser and operating system developers can roll out patches.
Here’s what users can do about it:
Avoid installing programs from suspicious sources. This will minimize the chances of malware infiltrating your system.
Learn how ClickFix attacks Lately, stealers have frequently been distributed using this specific malicious tactic.
Keep your OS and software updated on all devices. Timely updates help patch many of the vulnerabilities that malware exploits.
Install a robust security solution on all your devices. It’ll block suspicious activity in real time and alert you to potential threats.
As an added precaution, avoid storing passwords and bank card info in Google Chrome or your Notes app, as these are the first places any self-respecting stealer looks. Instead, use a secure password manager.
Stealers are hunting for your data, finding ways to infiltrate both computers and smartphones alike. To protect yourself from theft, check out our other related posts:
Cyber threats to water systems are no longer hypothetical. When attacks succeed, communities can face loss of trust, safety concerns, or service disruptions.
Today, Microsoft, in collaboration with the Cyber Readiness Institute (CRI) and the Center on Cyber Technology and Innovation (CCTI), is releasing a report that examines both the urgency of this challenge and what it will take to close the cyber readiness gap in the water sector. The report draws on a pilot program that provided water and wastewater utilities with practical cybersecurity training paired with hands‑on coaching, testing whether real-world support can meaningfully improve cyber readiness.
The findings point to a clear conclusion: improving cyber resilience in the water sector is achievable when training is paired with hands-on support and delivered through trusted sector partners. Because of the success of this pilot, the program is now a permanent offering, giving water utilities continued access to practical training and support to strengthen cyber resilience and better protect their communities from evolving threats.
Why cyber resilience in the water sector matters now
Water and wastewater utilities underpin public health, economic activity, and community resilience across all critical infrastructure. Yet recent assessments from the U.S. intelligence community and public reporting on cyber incidents underscore how exposed many systems remain. Even larger, well-resourced utilities have experienced cyber incidents, highlighting vulnerabilities that are far more pronounced among smaller operators serving rural and underserved communities.
Awareness of cyber risk is growing, but awareness is not preparedness. The challenge is how to move from growing awareness to sustained, operational readiness, especially for utilities with limited time, funding, and technical capacity.
What the pilot set out to test and what it showed
The CRI pilot was designed to answer a practical question facing the water sector: can accessible, behavior‑focused cybersecurity training paired with hands‑on support meaningfully improve cyber readiness?
Participating utilities used CRI’s free Cyber Readiness Program, which focuses on core cybersecurity practices such as strong authentication, software updates, phishing awareness, and secure data handling. Utilities also had access to CRI Certified Cyber Coaches, who worked directly with designated “Cyber Leaders” inside utilities to help translate training into policies, playbooks, and incident response planning. This model paired accessible training with personalized support to help utilities make meaningful progress despite resource constraints. The pilot revealed three clear findings about what helps and what limits cyber readiness in the water sector.
CRI program improves readiness: Participating utilities reported stronger cybersecurity fundamentals, greater confidence responding to incidents, and the identification of previously undocumented, yet critical, gaps such as missing continuity plans and weak password practices.
Hands-on support accelerates success: Utilities paired with a CRI‑certified coach were significantly more likely to complete the program than those participating on a self‑paced basis.
Demand exceeds capacity: While interest in cybersecurity support is high, staffing shortages, limited funding, and dependence on third-party vendors continue to limit utilities’ ability to fully implement improvements. Participation data helps explain this finding: of the 113 utilities that expressed initial interest, 72 began the program and 43 completed it.
Implications for policymakers and the ecosystem
The findings point to a central takeaway for policymakers and the ecosystem: improving cybersecurity outcomes requires moving beyond sharing information to providing hands-on support that helps utilities implement and sustain change.
Free resources are necessary but not enough: No-cost guidance alone cannot overcome staffing and funding constraints. Effective programs must include implementation support, like cyber coaches, to drive real outcomes.
Incentives increase participation: Tying cybersecurity training to operator licensing or continuing education requirements helps embed cyber readiness into routine professional development.
Trusted messengers drive engagement: Participation and completion were highest when programs were facilitated through established sector associations and networks that utilities already trust.
A path forward through collaboration
The lesson from this pilot is clear: cyber readiness improves when training is paired with hands‑on support and facilitated through trusted partners. But the findings also underscore a broader reality: lasting progress will require moving beyond information sharing toward approaches that build real, sustained capacity building on the ground.
At Microsoft, this work reflects a practical commitment to supporting cyber resilience across critical infrastructure, helping to move from awareness to action. Addressing the challenges identified in this report will require continued collaboration among policymakers, sector associations, nonprofits, and the private sector.
This work also complements Microsoft’s broader commitment to be water positive, including minimizing our water use and replenishing more water than we consume[1][2], by helping strengthen the resilience of the water systems and utilities that serve communities. Supporting practical cyber readiness is one way we can contribute to more resilient water systems for the future.
If you don’t go searching for AI services, they’ll find you all the same. Every major tech company feels a moral obligation not just to develop an AI assistant, integrated chatbot, or autonomous agent, but to bake it into their existing mainstream products and forcibly activate it for tens of millions of users. Here are just a few examples from the last six months:
Google activated Gemini for all U.S. Chrome users, cranked its browser functionality to the max, aggressively expanded the reach of AI Overviews in search results, and baked a whole suite of AI features into its online services (Gmail, Google Docs, and others).
Apple integrated its own Apple Intelligence (conveniently sharing the AI acronym) into the latest OS versions across all device types and most of its native apps.
On the flip side, geeks have rushed to build their own “personal Jarvises” by renting VPS instances or hoarding Mac minis to run the OpenClaw AI agent. Unfortunately, OpenClaw’s security issues with default settings turned out to be so massive that it’s already been dubbed the biggest cybersecurity threat of 2026.
Beyond the sheer annoyance of having something shoved down your throat, this AI epidemic brings some very real practical risks and headaches. AI assistants hoover up every bit of data they can get their hands on, parsing the context of the websites you visit, analyzing your saved documents, reading through your chats, and so on. This gives AI companies an unprecedentedly intimate look into every user’s life.
A leak of this data during a cyberattack — whether from the AI provider’s servers or from the cache on your own machine — could be catastrophic. These assistants can see and cache everything you can, including data usually tucked behind multiple layers of security: banking info, medical diagnoses, private messages, and other sensitive intel. We took a deep dive into how this plays out when we broke down the issues with the AI-powered Copilot+ Recall system, which Microsoft also planned to force-feed to everyone. On top of that, AI can be a total resource hog, eating up RAM, GPU cycles, and storage, which often leads to a noticeable hit to system performance.
For those who want to sit out the AI storm and avoid these half-baked, rushed-to-market neural network assistants, we’ve put together a quick guide on how to kill the AI in popular apps and services.
How to disable AI in Google Docs, Gmail, and Google Workspace
Google’s AI assistant features in Mail and Docs are lumped together under the umbrella of “smart features”. In addition to the large language model, this includes various minor conveniences, like automatically adding meetings to your calendar when you receive an invite in Gmail. Unfortunately, it’s an all-or-nothing deal: you have to disable all of the “smart features” to get rid of the AI.
To do this, open Gmail, click the Settings (gear) icon, and then select See all settings. On the General tab, scroll down to Google Workspace smart features. Click Manage Workspace smart feature settings and toggle off two options: Smart features in Google Workspace and Smart features in other Google products. We also recommend unchecking the box next to Turn on smart features in Gmail, Chat, and Meet on the same general settings tab. You’ll need to restart your Google apps afterward (which usually happens automatically).
How to disable AI Overviews in Google Search
You can kill off AI Overviews in search results on both desktops and smartphones (including iPhones), and the fix is the same across the board. The simplest way to bypass the AI overview on a case-by-case basis is to append -ai to your search query — for example, how to make pizza -ai. Unfortunately, this method occasionally glitches, causing Google to abruptly claim it found absolutely nothing for your request.
If that happens, you can achieve the same result by switching the search results page to Web mode. To do this, select the Web filter immediately below the search bar — you’ll often find it tucked away under the More button.
A more radical solution is to jump ship to a different search engine entirely. For instance, DuckDuckGo not only tracks users less and shows little ads, but it also offers a dedicated AI-free search — just bookmark the search page at noai.duckduckgo.com.
How to disable AI features in Chrome
Chrome currently has two types of AI features baked in. The first communicates with Google’s servers and handles things like the smart assistant, an autonomous browsing AI agent, and smart search. The second handles locally more utility-based tasks, such as identifying phishing pages or grouping browser tabs. The first group of settings is labeled AI mode, while the second contains the term Gemini Nano.
To disable them, type chrome://flags into the address bar and hit Enter. You’ll see a list of system flags and a search bar; type “AI” into that search bar. This will filter the massive list down to about a dozen AI features (and a few other settings where those letters just happen to appear in a longer word). The second search term you’ll need in this window is “Gemini“.
After reviewing the options, you can disable the unwanted AI features — or just turn them all off — but the bare minimum should include:
AI Mode Omnibox entrypoint
AI Entrypoint Disabled on User Input
Omnibox Allow AI Mode Matches
Prompt API for Gemini Nano
Prompt API for Gemini Nano with Multimodal Input
Set all of these to Disabled.
How to disable AI features in Firefox
While Firefox doesn’t have its own built-in chatbots and hasn’t (yet) tried to force upon users agent-based features, the browser does come equipped with smart-tab grouping, a sidebar for chatbots, and a few other perks. Generally, AI in Firefox is much less “in your face” than in Chrome or Edge. But if you still want to pull the plug, you’ve two ways to do it.
The first method is available in recent Firefox releases — starting with version 148, a dedicated AI Controls section appeared in the browser settings, though the controls are currently a bit sparse. You can use a single toggle to completely Block AI enhancements, shutting down AI features entirely. You can also specify whether you want to use On-device AI by downloading small local models (currently just for translations) and configure AI chatbot providers in sidebar, choosing between Anthropic Claude, ChatGPT, Copilot, Google Gemini, and Le Chat Mistral.
The second path — for older versions of Firefox — requires a trip into the hidden system settings. Type about:config into the address bar, hit Enter, and click the button to confirm that you accept the risk of poking around under the hood.
A massive list of settings will appear along with a search bar. Type “ML” to filter for settings related to machine learning.
To disable AI in Firefox, toggle the browser.ml.enabled setting to false. This should disable all AI features across the board, but community forums suggest this isn’t always enough to do the trick. For a scorched-earth approach, set the following parameters to false (or selectively keep only what you need):
ml.chat.enabled
ml.linkPreview.enabled
ml.pageAssist.enabled
ml.smartAssist.enabled
ml.enabled
ai.control.translations
tabs.groups.smart.enabled
urlbar.quicksuggest.mlEnabled
This will kill off chatbot integrations, AI-generated link descriptions, assistants and extensions, local translation of websites, tab grouping, and other AI-driven features.
How to disable AI features in Microsoft apps
Microsoft has managed to bake AI into almost every single one of its products, and turning it off is often no easy task — especially since the AI sometimes has a habit of resurrecting itself without your involvement.
How to disable AI features in Edge
Microsoft’s browser is packed with AI features, ranging from Copilot to automated search. To shut them down, follow the same logic as with Chrome: type edge://flags into the Edge address bar, hit Enter, then type “AI” or “Copilot” into the search box. From there, you can toggle off the unwanted AI features, such as:
Enable Compose (AI-writing) on the web
Edge Copilot Mode
Edge History AI
Another way to ditch Copilot is to enter edge://settings/appearance/copilotAndSidebar into the address bar. Here, you can customize the look of the Copilot sidebar and tweak personalization options for results and notifications. Don’t forget to peek into the Copilot section under App-specific settings — you’ll find some additional controls tucked away there.
How to disable Microsoft Copilot
Microsoft Copilot comes in two flavors: as a component of Windows (Microsoft Copilot), and as part of the Office suite (Microsoft 365 Copilot). Their functions are similar, but you’ll have to disable one or both depending on exactly what the Redmond engineers decided to shove onto your machine.
The simplest thing you can do is just uninstall the app entirely. Right-click the Copilot entry in the Start menu and select Uninstall. If that option isn’t there, head over to your installed apps list (Start → Settings → Apps) and uninstall Copilot from there.
In certain builds of Windows 11, Copilot is baked directly into the OS, so a simple uninstall might not work. In that case, you can toggle it off via the settings: Start → Settings → Personalization → Taskbar→ turn off Copilot.
If you ever have a change of heart, you can always reinstall Copilot from the Microsoft Store.
It’s worth noting that many users have complained about Copilot automatically reinstalling itself, so you might want to do a weekly check for a couple of months to make sure it hasn’t staged a comeback. For those who are comfortable tinkering with the System Registry (and understand the consequences), you can follow this detailed guide to prevent Copilot’s silent resurrection by disabling the SilentInstalledAppsEnabled flag and adding/enabling the TurnOffWindowsCopilot parameter.
How to disable Microsoft Recall
The Microsoft Recall feature, first introduced in 2024, works by constantly taking screenshots of your computer screen and having a neural network analyze them. All that extracted information is dumped into a database, which you can then search using an AI assistant. We’ve previously written in detail about the massive security risks Microsoft Recall poses.
Under pressure from cybersecurity experts, Microsoft was forced to push the launch of this feature from 2024 to 2025, significantly beefing up the protection of the stored data. However, the core of Recall remains the same: your computer still remembers your every move by constantly snapping screenshots and OCR-ing the content. And while the feature is no longer enabled by default, it’s absolutely worth checking to make sure it hasn’t been activated on your machine.
To check, head to the settings: Start → Settings → Privacy & Security →Recall & snapshots. Ensure the Save snapshots toggle is turned off, and click Delete snapshots to wipe any previously collected data, just in case.
How to disable AI in Notepad and Windows context actions
AI has seeped into every corner of Windows, even into File Explorer and Notepad. You might even trigger AI features just by accidentally highlighting text in an app — a feature Microsoft calls “AI Actions”. To shut this down, head to Start → Settings → Privacy & Security → Click to Do.
Notepad has received its own special Copilot treatment, so you’ll need to disable AI there separately. Open the Notepad settings, find the AI features section, and toggle Copilot off.
Finally, Microsoft has even managed to bake Copilot into Paint. Unfortunately, as of right now, there is no official way to disable the AI features within the Paint app itself.
How to disable AI in WhatsApp
In several regions, WhatsApp users have started seeing typical AI additions like suggested replies, AI message summaries, and a brand-new Chat with Meta AI button. While Meta claims the first two features process data locally on your device and don’t ship your chats off to their servers, verifying that is no small feat. Luckily, turning them off is straightforward.
To disable Suggested Replies, go to Settings → Chats → Suggestions & smart replies and toggle off Suggested replies. You can also kill off AI Sticker suggestions in that same menu. As for the AI message summaries, those are managed in a different location: Settings → Notifications → AI message summaries.
How to disable AI on Android
Given the sheer variety of manufacturers and Android flavors, there’s no one-size-fits-all instruction manual for every single phone. Today, we’ll focus on killing off Google’s AI services — but if you’re using a device from Samsung, Xiaomi, or others, don’t forget to check your specific manufacturer’s AI settings. Just a heads-up: fully scrubbing every trace of AI might be a tall order — if it’s even possible at all.
In Google Messages, the AI features are tucked away in the settings: tap your account picture, select Messages settings, then Gemini in Messages, and toggle the assistant off.
Broadly speaking, the Gemini chatbot is a standalone app that you can uninstall by heading to your phone’s settings and selecting Apps. However, given Google’s master plan to replace the long-standing Google Assistant with Gemini, uninstalling it might become difficult — or even impossible — down the road.
If you can’t completely uninstall Gemini, head into the app to kill its features manually. Tap your profile icon, select Gemini Apps activity, and then choose Turn off or Turn off and delete activity. Next, tap the profile icon again and go to the Connected Apps setting (it may be hiding under the Personal Intelligence setting). From here, you should disable all the apps where you don’t want Gemini poking its nose in.
Apple’s platform-level AI features, collectively known as Apple Intelligence, are refreshingly straightforward to disable. In your settings — on desktops, smartphones, and tablets alike — simply look for the section labeled Apple Intelligence & Siri. By the way, depending on your region and the language you’ve selected for your OS and Siri, Apple Intelligence might not even be available to you yet.
Other posts to help you tune the AI tools on your devices:
Attackers are abusing normal OAuth error redirects to send users from a legitimate Microsoft or Google login URL to phishing or malware pages, without ever completing a successful sign‑in or stealing tokens from the OAuth flow itself.
That calls for a bit more explanation.
OAuth (Open Authorization) is an open-standard protocol for delegated authorization. It allows users to grant websites or applications access to their data on another service (for example, Google or Facebook) without sharing their password.
OAuth redirection is the process where an authorization server sends a user’s browser back to an application (client) with an authorization code or token after user authentication.
Researchers found that phishers use silent OAuth authentication flows and intentionally invalid scopes to redirect victims to attacker-controlled infrastructure without stealing tokens.
So, what does this attack look like from a target’s perspective?
From the user’s perspective, the attack chain looks roughly like this:
The email
An email arrives with a plausible business lure. For example, you receive an email about something routine but urgent: document sharing or review, a Social Security or financial notice, an HR or employee report, a Teams meeting invite, or a password reset.
The email body contains a link such as “View document” or “Review report,” or a PDF attachment that includes a link instead.
The link
You click the link after seeing that it appears to be a normal Microsoft or Google login. The visible URL (what you see when you hover over it) looks convincing, starting with a trusted domain like https://login.microsoftonline.com/ or https://accounts.google.com/.
There is no obvious sign that the parameters (prompt=none, odd or empty scope, encoded state) are abnormal.
Silent OAuth
The crafted URL attempts a silent OAuth authorization (prompt=none) and uses parameters that are guaranteed to fail (for example, an invalid or missing scope).
The identity provider evaluates your session and conditional access, determines the request cannot succeed silently, and returns an OAuth error, such as interaction_required, access_denied, or consent_required.
The redirect
By design, the OAuth server then redirects your browser, including the error parameters and state, to the app’s registered redirect URI, which in these cases is the attacker’s domain.
To the user, this is just a quick flash of a Microsoft or Google URL followed by another page. It’s unlikely anyone would notice the errors in the query string.
Landing page
The target gets redirected to a page that looks like a legitimate login or business site. This could very well be a clone of a trusted brand’s site.
From here, there are two possible malicious scenarios:
Phishing / Attacker in the Middle (AitM) variant
A normal login page or a verification prompt, sometimes with CAPTCHAs or interstitials to look more trustworthy and bypass some controls.
The email address may already be filled in because the attackers passed it through the state parameter.
When the user enters credentials and multi-factor authentication (MFA), the attacker‑in‑the‑middle toolkit intercepts them, including session cookies, while passing them along so the experience feels legitimate.
Malware delivery variant
Immediately (or after a brief intermediate page), the browser hits a download path and automatically downloads a file.
The context of the page matches the lure (“Download the secure document,” “Meeting resources,” and so on), making it seem reasonable to open the file.
The target might notice the initial file open or some system slowdown, but otherwise the compromise is practically invisible.
Potential impact
By harvesting credentials or planting a backdoor, the attacker now has a foothold on the system. From there, they may carry out hands-on-keyboard activity, move laterally, steal data, or stage ransomware, depending on their goals.
The harvested credentials and tokens can be used to access email, cloud apps, or other resources without the need to keep malware on the device.
How to stay safe
Since the attacker does not need your token from this flow (only the redirect into their own infrastructure), the OAuth request itself may look less suspicious. Be vigilant and follow our advice:
If you rely on hovering over links, be extra cautious when you see very long URLs with oauth2, authorize, and lots of encoded text, especially if they come from outside your organization.
Even if the start of the URL looks legitimate, verify with a trusted sender before clicking the link.
If something urgent arrives by email and immediately forces you through a strange login or starts a download you did not expect, assume it is malicious until proven otherwise.
If you are redirected somewhere unfamiliar, stop and close the tab.
Be very wary of files that download immediately after clicking a link in an email, especially from /download/ paths.
If a site says you must “run” or “enable” something to view a secure document, close it and double-check which site you’re currently on. It might be up to something.
Keep your OS, browser, and your favorite security tools up to date. They can block many known phishing kits and malware downloads automatically.
Pro tip: use Malwarebytes Scam Guard to help you determine whether the email you received is a scam or not.
We don’t just report on scams—we help detect them
Cybersecurity risks should never spread beyond a headline. If something looks dodgy to you, check if it’s a scam using Malwarebytes Scam Guard. Submit a screenshot, paste suspicious content, or share a link, text or phone number, and we’ll tell you if it’s a scam or legit. Available with Malwarebytes Premium Security for all your devices, and in the Malwarebytes app for iOS and Android.
Microsoft issued an emergency patch for a high-severity zero-day vulnerability in Office that allows attackers to bypass document security checks and is being exploited in the wild via malicious files.
Microsoft pushed the emergency patch for the zero‑day, tracked as CVE-2026-21509, and classified it as a “Microsoft Office Security Feature Bypass Vulnerability” with a CVSS score of 7.8 out of 10.
The flaw allows attackers to bypass Object Linking and Embedding (OLE) mitigations that are designed to block unsafe COM/OLE controls inside Office documents. This means a malicious attachment could infect a PC despite built-in protections.
In a real-life scenario, an attacker creates a fake Word, Excel, or PowerPoint file containing hidden “mini‑programs” or special objects. They can run code and do other things on the affected computer. Normally, Office has safety checks that would block those mini-programs because they’re risky.
However, the vulnerability allows the attacker to tweak the file’s structure and hidden information in a way that tricks Office into thinking the dangerous mini‑program inside the document is harmless. As a result, Office skips the usual security checks and allows the hidden code to run.
As code to test the bypass is publicly available, increasing the risk of exploitation, users are under urgent advice to apply the patch.
Updating Microsoft 365 and Office
How to protect your system
What you need to do depends on which version of Office you’re using.
The affected products include Microsoft Office 2016, 2019, LTSC 2021, LTSC 2024, and Microsoft 365 Apps (both 32‑bit and 64‑bit).
Office 2021 and later are protected via a server‑side change once Office is restarted. To apply it, close all Office apps and restart them.
Office 2016 and 2019 require a manual update. Run Windows Update with the option to update other Microsoft products turned on.
If you’re running build 16.0.10417.20095 or higher, no action is required. You can check your build number by opening any Office app, going to your account page, and selecting About for whichever application you have open. Make sure the build number at the top reads 16.0.10417.20095 or higher.
What always helps:
Don’t open unsolicited attachments without verifying them with a trusted sender.
Treat all unexpected documents, especially those asking to “enable content” or “enable editing,” as suspicious.
Keep macros disabled by default and only allow signed macros from trusted publishers.
rvrsh3ll // Introduction This blog post is intended to give a light overview of device codes, access tokens, and refresh tokens. Here, I focus on the technical how-to for standing […]
Sally Vandeven // We have all heard people talk about how much cooler Linux is than Windows, so much easier to use, etc. Well, they are not necessarily wrong… but we […]
Sally Vandeven & David Fletcher // This is the podcast version of Sally & David’s webcast. For the whole webcast see our webcast post. Links that are mentioned in this […]
David Fletcher & Sally Vandeven// Join David “Fletch” and Sally as they explore the cornucopia of wonderful, free tools in the SysInternals Suite that conveniently are signed by Microsoft and […]
Carrie Roberts* // Can you think of a reason why you might want to put a lengthy comment into the properties of an MS Office document? If you can, then […]
Jordan Drysdale & Kent Ickler // In this webcast, we demonstrate some standard methodologies utilized during an internal network review. We also discuss various tools used to test network defenses […]
Beau Bullock // Overview Microsoft Exchange users have the power to grant other users various levels of access to their mailbox folders. For example, a user can grant other users […]
Ethan Robish // In my last two posts I showed how to insert tracking bugs in both .docx (Part 1) and .xlsx files (Part 2). But don’t let all that effort go […]
Ethan Robish // If you’re familiar with ADHD and Web Word Bugs, you likely already know the method to create web tracking software using .html files renamed as .doc files. […]
Beau Bullock // Full Disclosure: Black Hills Information Security believes in responsible disclosure of vulnerabilities. This vulnerability was reported to Microsoft on September 28th, 2016. As of the publication date of […]
Lawrence Hoffman // So Microsoft is open sourcing PowerShell and putting it on Linux. Realistically Linux already has a full suite of administrative tools and some very powerful scripting languages […]
Lawrence Hoffmann // So, Apple announced a new bug bounty program at BlackHat, and there are some interesting deviations from the norm in their plan to implement and pay out. […]
Carrie Roberts // Answer: Enough to make it worth it! Penetration testers love to perform password spraying attacks against publicly available email portals as described here in this great post by Beau Bullock. […]
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