Microsoft has confirmed that the KB5120998 August 2026 non-security preview update is reverting mouse settings on Windows 11 systems. According to user reports, mouse cursor personalization settings are either being changed or reset automatically after installing the KB5120998 update. More importantly, affected Windows 11 users will not be able to restore the previous mouse settings after they are reverted. "Microsoft has received reports indicating that mouse cursor personalization settings are being changed or reverted to certain standard settings. This occurs following installation of Windows updates released August 27 2026 (KB5120998) and later," Microsoft explained. "The issue is described as resulting in appearance regressions and intermittent animation changes. Some reports mention that high-DPI mouse cursors are replaced with larger, white cursors, and custom cursor animations reverting to standard settings. Attempts to restore the previous cursor customization are reported to be unsuccessful."
Learn how the Spring Ring campaign abuses Microsoft Teams and voice phishing to deploy malware and target enterprise domain controllers. The post Spring Ring: An Inside Look at Voice Phishing Campaigns in Microsoft Teams appeared first on Unit 42.
Attackers typically try to pass off malware as legitimate applications or as potentially unwanted programs that users deliberately search for and download, such as cheats or cracks. They often rely on ad and affiliate networks to deliver their creations to victims’ devices. This post examines a less conventional case: a well-known backdoor distributed under the guise of adware. The attackers may have chosen this distribution method because the adware was signed by the developer. On top of that, users often manually add these apps to exclusions, so their useful features don’t get blocked. Some time ago, a client asked us to analyze a file with the MD5 hash c24e99f9437feacaa63766a3cde3fe3d and add it to our detection database. We initially classified it as adware, but a cursory analysis turned up suspicious network activity, which prompted us to dig deeper. It turned out the sample did far more than serve ads. In fact, its advertising functionality doesn’t even work; instead, it triggers an infection chain that delivers the ValleyRAT backdoor. Malicious installer The file the client shared with us turned out to be an installer that performed different actions depending on the two-letter suffix used in the file name, positioned just before the numeric string. Installer name What it does FS_SETUP_DD_173.exe Installs DingTalk, a workplace collaboration platform FS_SETUP_GG_173.exe Installs Google Chrome FS_SETUP_HY_173.exe Opens hxxps://meeting[.]tencent[.]com/download/ These actions are most likely designed to divert the user’s attention away from the sample’s malicious functionality. Regardless of the file name, the installer deploys a modified Chinese desktop wallpaper management tool called QN Wallpaper (hxxps://qnwallpaper[.]keansoft[.]cn/) and adds it to the registry’s autorun entries. The original version of QN Wallpaper is genuine adware: on installation, it delivers bundled partner apps to the device and then displays ad banners to the user. In this case, however, the attackers use it to carry out DLL sideloading, a technique that allows malicious code to run under the guise of a signed process by way of a malicious DLL. The QN Wallpaper modules, along with the malicious components, are unpacked to C:\Program Files\QNWallpaper\5.4.0.1662\<random string of letters and digits>. The following files are saved in that directory: File name MD5 Purpose 1.zip 7ad1e3ef4e6d9d636c9e7e967733850e Archive containing the adware files QnWallpeper.exe and QnwPlayer.exe, along with the modules needed to run them 7z.dll 96b4c1d0683dce22bd3223e1e40689c1 7z archiver library 7z.exe 9b86d3ab6cef15c633933fbbeab39c0a Archiver chrome_elf.dll edfdc30cbd85879776b8f735ea7de1f1 Library used to launch Electron-based applications libcef.dll 07ddbbe2c71c45577a7a4fbcdba0df91 Malicious library PeLoader 48826d5ca845979d2e6ebd66dc1aae90 File containing the encrypted backdoor QnWallpaper.exe 6c158c0f8e029342192d4f0d72e102b7 Adware module QnwPlayer.exe 9a71d6a41cd258b9e89cdc5fc224de73 Adware module <random string of letters and digits>Nedca.exe c24e99f9437feacaa63766a3cde3fe3d Malicious installer copy After unpacking, the installer uses the DisableAntiSpyware registry key to disable Windows Defender and then launches QnWallpaper.exe. Disabling Windows Defender DLL Sideloading via libcef.dll QnWallpaper.exe has dependencies in libcef.dll, so this library gets loaded when the process starts. QnWallpaper.exe also launches QnwPlayer.exe, which likewise calls libcef.dll. QnWallpaper and QnwPlayer won’t actually function correctly, because the functions exported from libcef.dll are put into an infinite sleep. However, in case that sleep is ever interrupted, the attackers have implemented a function that loads all the necessary functions from the original library into memory, provided it can locate that library on the system. Example of an exported function Loading functions from the original libcef.dll The malicious functionality in libcef.dll is invoked by a call to DllMain, which runs automatically when the library is loaded. That said, alongside the original exports, the library also contains a function named RunDLL, which likewise initiates execution of the malicious code. QnWallpaper never calls this function. We suspect the attackers intended to invoke it manually via rundll32 or planned to use a separate executable for this purpose, one that wasn’t included in the package downloaded by the sample. The RunDLL function Running the malicious code When the library is loaded, code runs that ensures QnWallpaper.exe persists at startup: it adds a file extension association and drops a file with the corresponding extension in C:\Documents and Settings\<username>\Start Menu\Programs\Startup\. This is followed by a chain of wrapper functions whose main job is to call the next one. Execution eventually reaches the function that contains the actual malicious code. For convenience, we’ll refer to it as mw_entry. Inside mw_entry, the malware checks two things: Whether the current user belongs to the Administrators group Which process the DLL is running inside Checking for administrator privileges If the user isn’t a member of the Administrators group, the program attempts to obtain administrator privileges by using the runas utility. Relaunching the process to obtain administrator privileges Once it has administrator privileges, the malicious code determines which process the DLL has been loaded into, and selects the payload accordingly: If the library is running inside QnWallpaper.exe, the payload is loaded from the PeLoader file. Encrypted payload If the library is running inside QnwPlayer.exe, the payload is loaded from libcef.dll resources. Retrieving the payload from a resource Both payloads are AES-encrypted DLLs that contain the ValleyRAT backdoor. The only difference between them is their configuration, specifically, the C2 server addresses. After decryption, libcef.dll checks the magic signatures in the resulting PE file’s headers to confirm the sample is valid. If this check fails, the library releases its resources and takes no further action. Validating the PE file headers after decryption If the headers check out, libcef.dll loads the payload into the process’s memory space and hands control over to the backdoor by calling DllMain. Calling DllMain ValleyRAT ValleyRAT begins its operation by parsing its configuration, which consists of key:value pairs concatenated into a single string. To obfuscate this configuration, the attackers wrote the string in reverse. Obfuscated configuration During parsing, the backdoor restores the correct character order and reads the key values one by one. The set of keys is the same regardless of which process the backdoor is running in. Parsing the configuration Some of the configuration fields are listed below: Key Description p? C2 server IP address o? C2 server port t? Protocol (1: TCP, 0: UDP) dd Sleep duration before executing the main code cl Sleep duration after receiving the corresponding command from the server bz Configuration creation date bh Whether to mark the current process as critical (so that terminating it triggers a blue screen of death) Possible values: 1: yes, 0: no ll Whether to check for running security/traffic-analysis tools/processes (1: check, 0: do not check) sh Whether to inject code into svchost that will restart the malicious process (1: inject, 0: do not inject) The backdoor uses several techniques to protect its process. Some are configuration-dependent, while others are always applied: Injecting code into svchost to restart the process: a configurable option. The backdoor allocates memory inside the svchost process, injects code into it, and sets PAGE_NOACCESS permissions on the memory page containing the injected data. It then creates a suspended thread, waits 60 seconds, grants read, write, and execute permissions on the page, and resumes the thread. Injecting code into svchost The function injected into the process has a single job: restart the backdoor if its execution is interrupted for any reason. Injected function Marking its own process as critical (so that terminating it triggers a blue screen of death): a configurable option. Setting its own process as critical Restarting on an unhandled exception. This protection mechanism is always active, regardless of the backdoor’s configuration. Restarting on exceptions The backdoor also has spyware functionality. While running, it tracks keystrokes and the currently focused window by using functions from the DirectInput8 library. It also captures clipboard contents. All collected data is saved to a file on disk. Capturing clipboard data If the ll key in the configuration is set to 1, ValleyRAT periodically checks for active windows belonging to applications that could be used to analyze processes or traffic. Window enumeration is done via the EnumWindows function, using the following callback: Window name checks After completing these checks, the backdoor collects system information, including: Host name Host IP addresses User idle time Detailed Windows version information (ProductName, EditionId, DisplayVersion) Number of CPU cores Free disk space Graphics adapter Currently focused window and its title System bitness Language settings Path to the system directory On command, the backdoor can perform the actions typical of this malware category: Rebooting the computer Shutting down the computer Taking a screenshot Wiping logs Updating its C2 addresses Downloading additional modules Sending keylogger logs along with clipboard contents Snippet of the command handler Let’s take a closer look at the module-loading functionality. Upon receiving the corresponding command with a link from its operator, the backdoor downloads the file at that link and executes it. The download can come from either the C2 server or a third-party address. The DownloadPeFile function is responsible for downloading a PE file The DownloadAndExecute function calls DownloadPeFile, then launches the downloaded module Additional modules can take the form of purpose-built dynamic libraries or shellcode. If the payload is shellcode, the backdoor uses process hollowing with svchost to launch the module. Implementation of the process hollowing technique If the module is a dynamic library, the backdoor loads the PE file into its own process, calls DllMain, and searches for a Main function among the exported functions. Once Main has been called, the library is unloaded from memory. Calling DllMain after the backdoor loads the PE file Targets and attribution Over the course of 2026, we detected the ValleyRAT backdoor and its associated malware more than 100,000 times, with more than 1500 unique users affected, primarily in China and India. This attack geography, combined with the use of the ValleyRAT backdoor, points to Silver Fox, a known operator of this malware family, as the likely group behind the campaign. Conclusion This case is a clear example of how adware and affiliate networks can turn out to be far more dangerous than they appear. ValleyRAT is a sophisticated backdoor capable of collecting sensitive data such as keystrokes and clipboard contents, taking screenshots, and delivering additional malicious modules. The attackers exploited a well-known adware application to run the backdoor under the guise of a signed process, which complicates detection. Motivated by both cyberespionage and financial gain, Silver Fox targets organizations across multiple countries. To stay protected, organizations should keep employee cybersecurity awareness up to date and enforce clear policies on the use of third-party software on work devices. For individual users, we recommend avoiding the installation of software with a questionable reputation, and, even more importantly, never adding such software to your security solutions’ exclusion lists. IoC MD5 07ddbbe2c71c45577a7a4fbcdba0df91 c24e99f9437feacaa63766a3cde3fe3d 8a626d844943da3456b044f38deae3a2 Network 103.45.66.18:441 103.45.66.18:442 103.45.66.18:443 192.253.225.173:6666 192.253.225.173:8888
Two Nigerian men extradited to the U.S. on Thursday have been charged with involvement in sextortion schemes that resulted in the deaths of two minor victims in Mississippi and North Carolina. Sextortion is a form of online blackmail in which cybercriminals threaten victims with leaking nude images and videos they stole (through hacking) or obtained (through coercion). In some cases, they may also sell the stolen content on criminal marketplaces or share the victims' personal information (including names, dates of birth, emails, phone numbers, and social media usernames) with other criminals, who can use it to further pressure them into providing additional private images and videos. 26-year-old Adebola Festus Adekunle and 24-year-old Mudasiru Afeez Olawale were both arrested in Nigeria in August 2023 as part of "Operation Artemis," a joint international law enforcement action that targets sextortion rings operating from Nigeria who prey on minors in the United States.
Infostealers can steal active Claude sessions, bypass 2FA and drain paid usage. Anthropic is revoking access and refunding unauthorized charges. Anthropic confirmed that several infostealer malware can hijack an active Claude login session and let attackers burn through your usage without ever touching your password. “Our investigation is ongoing. Our findings to date suggest that a computer you use with Claude is likely infected with infostealer malware, and may have been for some time. Phones and tablets do not appear to have been involved.” reads the notification sent to the impacted users. “We have no reason to believe that this malware is related to Claude, installed through Claude, or related to anything you did with Claude. It’s general-purpose malware that typically arrives with an unofficial download or a malicious app, and it quietly copies saved passwords, login cookies in browsers, and credentials for other apps running locally. Your Claude session was likely one of the many things it collected. It appears that a bad actor has now started picking the Claude sessions out of what it collected and using them.” Recently, Anthropic started signing some Claude users out and removing their saved payment cards. The reason? Infostealer malware on their computers stole active Claude sessions and gave attackers access to their accounts. “We recently signed you out of Claude and removed the payment method saved on your account, so you’ll need to log back in and re-add your card.” continues the report. “We’re sorry for the disruption. Here’s what happened and what we’ve done about it.” Anthropic detected the suspicious activity and identified multiple infostealer families affecting Windows and macOS. Infostealers bypass the login process by stealing authenticated browser sessions, allowing attackers to evade passwords, MFA and SSO and access paid Claude accounts. Revoking sessions or blocking fraudulent payments is not enough: if the malware remains on the device, it can capture the user’s next login and give attackers access again. Anthropic is also refunding users for any charges it identifies as unauthorized. BREAKING: Anthropic is signing Claude users out and deleting their saved card because infostealer malware on their machines handed a bad actor live Claude login sessions. Anthropic says its systems detected the activity, and the notification names six stealer families across… pic.twitter.com/0nX53PaeiH — International Cyber Digest (@IntCyberDigest) August 29, 2026 “”Our systems detected this activity on your account, and we’ve therefore removed your card on file and signed out the sessions involved to help block further unauthorized access.” continues the report. “If your usage limits looked like they refilled and then drained while you weren’t using Claude, this was likely the cause.”” Anthropic identified Vidar, LummaC2, StealC, RedLine and Acreed on Windows, plus Atomic Stealer on a small number of Macs. The company revoked affected Claude sessions, forcing users to log in again, and removed saved payment methods to prevent unauthorized charges. Existing plans will continue until the current billing period ends. After that, users will need to add their payment method again. Anthropic may also sign them out again if it detects suspicious activity. If you use Claude and haven’t checked your usage history recently, that’s worth doing today rather than next week. Anthropic’s advice is the standard but genuinely necessary response: run a full malware scan before logging back in, change your account password with two-factor authentication enabled, and treat any pirated download or unofficial app installer with the same suspicion you’d give a sketchy email attachment. An AI subscription being quietly drained isn’t the scariest thing an infostealer can do to you, but it’s a pretty reliable sign that something considerably worse, like your actual banking credentials, might already be sitting in the same haul. Follow me on Twitter: @securityaffairs and Facebook and Mastodon Pierluigi Paganini (SecurityAffairs – hacking, Anthropic)
Microsoft asked customers this week to ignore incorrect alerts that Defender Antivirus has been turned off after installing the latest Defender updates. Although this issue has been affecting users in the Release Preview Channel of the Windows Insider program since June, it appears Microsoft didn't notice it until now. The erroneous alerts appear on affected systems in the Windows Security app and prompt users to "Tap or click to turn on Microsoft Defender Antivirus." The known issue affects all supported Windows client and server versions, including the latest Windows 11 26H1 and Windows Server 2025 releases. "After installing the latest updates for Microsoft Defender Antivirus, notifications might appear stating that "Microsoft Defender Antivirus is turned off," even though the antivirus is functioning correctly and all settings show it as active," Microsoft explained in a Friday release health dashboard update.
A critical GiveWP flaw lets unauthenticated attackers execute server commands. Version 4.16.7.2 fixes the PHP object injection chain. A critical vulnerability in GiveWP, one of the most widely used WordPress plugins for online donations and fundraising, can let an unauthenticated attacker execute commands on the server. Patchstack disclosed the flaw on August 28, after researcher Udin Chan reported it on July 28, and GiveWP fixed it in version 4.16.7.2 released on August 27. The issue, tracked as CVE-2026-82222 (CVSS score of 10.0), affects GiveWP versions through 4.16.7.1. An attacker doesn’t need an account or user interaction to exploit the underlying vulnerability. “In versions 4.16.7.1 and below, GiveWP contains an unauthenticated PHP Object Injection vulnerability that can be chained into full remote code execution. On 4.16.5.1 and below a default installation is enough to exploit: it ships with an active manual (Test Donation) gateway and an active offline gateway, and only needs one published donation form.” reads the report published by PatchStack. “No Test Mode, open registration, debug mode, or administrator action is required.” That description sounds severe because it is. The problem isn’t one isolated coding mistake. Patchstack found a chain involving unsafe handling of serialized PHP objects, a donation workflow that can carry attacker-controlled data into storage, and classes already included in GiveWP that can turn the injected object into command execution. GiveWP is designed for nonprofits and other organizations that collect donations through WordPress. The plugin handles donation forms, payment gateways, donor information and reporting, so a server running it can hold data that attackers would have plenty of reasons to target. The root cause of the problem is a helper that GiveWP created to make PHP’s unserialize() safer. It uses PHP’s allowed_classes => false option, which looks like a sensible defense at first glance. There’s a catch. PHP doesn’t simply throw the serialized object away. Instead, it converts the object into an __PHP_Incomplete_Class placeholder while keeping the original class name and properties. When GiveWP later serializes that placeholder again, those original object details go back into the serialized data. The application has effectively carried the attacker’s payload forward instead of removing it. That distinction matters because the malicious object eventually reaches another part of GiveWP that reads the stored data without the same restriction. At that point, PHP can recreate the original object and the rest of the attack chain can continue. The donation process gives the attacker a way to move that malicious data into GiveWP’s session storage. Patchstack found that the application reads donor information from the user’s account and sends the fields through the supposedly safe unserialization helper. The attacker-controlled data can therefore survive the first check and reach the wp_give_sessions table. A later request reads the session and processes the serialized object again, this time without the protection that was supposed to stop it. This is a classic example of why serialization bugs can be difficult to contain. Checking data at one point doesn’t help much if the application later stores that data and processes it differently somewhere else. The object injection alone doesn’t automatically mean arbitrary command execution. An attacker also needs a gadget chain, meaning existing application code that can be manipulated to turn the injected object into a dangerous operation. Patchstack found that GiveWP ships code that provides exactly that missing piece. The chain involves the TCPDF library and GiveWP’s own Give\TestData classes, eventually reaching a function call controlled by properties inside the injected object. “Because loadedProviders is just an array property carried inside the injected object, the attacker sets it to any callable they like.” continues the report. “Pointing it at system() executes an arbitrary OS command as the web server user.” That means the attacker can turn control of the object into control of what function the application calls. In the vulnerable code, that can lead to execution of an operating system command with the privileges of the web server. At that point, this stops being a data-handling problem and becomes a server compromise problem. If the WordPress process has access to sensitive files, databases or other internal resources, the impact can extend well beyond the GiveWP plugin itself. GiveWP’s registration feature ignores WordPress’s users_can_register setting, allowing attackers to create accounts even when registration is disabled. Version 4.16.6 added a nonce check, but attackers can still obtain and reuse the nonce on sites with the public registration shortcode. Patchstack says versions 4.16.5.1 and earlier are directly exploitable on default installations. Versions 4.16.6–4.16.7.1 reduce the attack surface but leave the underlying flaw exploitable through legacy forms. Version 4.16.7.2 fully fixes the issue. GiveWP 4.16.7.2 takes a broader approach to fixing the RCE. It blocks serialized data before storage, limits where stored data can be deserialized, hardens the vulnerable gadget and sanitizes donor and billing metadata. It also scans existing database records and removes serialized objects that could contain malicious payloads. This cleanup matters because updating the code alone cannot remove data already stored by an attacker. Patchstack also found that the earlier 4.16.6 fix could preserve malicious serialized data after detecting __PHP_Incomplete_Class; 4.16.7.2 rejects it instead. Administrators should update to 4.16.7.2 or later, review logs and signs of compromise, and check older or imported donation forms. The separate registration issue remains unresolved, but Patchstack treats it as an access-control problem rather than part of the patched RCE chain. Follow me on Twitter: @securityaffairs and Facebook and Mastodon Pierluigi Paganini (SecurityAffairs – hacking, GiveWP)
The Manchester Airports Group data breach has been claimed by extortion group FulcrumSec, which told BleepingComputer that it stole approximately 86 GB of data. Samples reviewed by BleepingComputer contained information consistent with MAG's disclosure while indicating that the breach exposed considerably more detailed customer, booking, and travel information than initially revealed. Manchester Airports Group (MAG), the United Kingdom's largest airport operator, disclosed on August 27 that an unauthorized third party had stolen customer data related to Manchester, London Stansted, and East Midlands airports. The company said the affected information came from car park, lounge, and Fast Track bookings and in-airport Wi-Fi registrations. In emails to BleepingComputer, FulcrumSec claimed responsibility for the attack and shared samples of the allegedly stolen data as evidence.
Anthropic is warning some Claude users that infostealer malware on their PCs has stolen active Claude login sessions, allowing attackers to access accounts and consume their usage. The company is signing affected users out of Claude, removing saved payment methods, and refunding charges it identifies as unauthorized. "We have recently become aware of a bad actor that is using common infostealer malware to steal Claude login sessions from people's computers, then using those login sessions to access Claude accounts and consume their usage," Anthropic said in an email sent to an affected user, who shared it on Reddit. "If your usage limits looked like they refilled and then drained while you weren't using Claude, this was likely the cause," Anthropic warned. It is also worth noting that infostealers can copy an already authenticated browser session, which means the attacker may not need to go through the normal password and 2FA login process again.
Multiple extensions for Google Chrome and Microsoft Edge delivered a malware framework that deployed modules to steal cryptocurrency, sensitive data, and browser history, and to inject ClickFix lures. Researchers say all 16 malicious modules uncovered in the campaign serve distinct purposes and are designed to be "highly extensible." The operation was uncovered by application security company Socket, and the investigation indicates that it may have been active since early 2024. Socket says that when initially published on the Chrome Web Store, many of the extensions provided the advertised functionality and contained no malware. According to the researchers, five of the extensions were acquired from their original creators and injected with malware via updates delivered automatically. One example is the "Enable Right Click & Copy — Smart Unlock + OCR" extension, the only one in the campaign available for both Chrome and Edge, which had a Chrome user base of at least 70,000 when it turned malicious. The number of installs on Edge was 10,000 at the time.
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