ValleyRAT hides behind legitimate adware, using DLL sideloading to evade detection, steal data and give Silver Fox control of infected systems. ValleyRAT doesn’t always need to disguise itself as a cracked game or a fake browser update. It can also hide behind something much more ordinary: an application that looks like adware and appears to serve a legitimate purpose. Kaspersky’s latest analysis shows how this works. Researchers found a malicious installer that uses a modified version of QN Wallpaper, a legitimate Chinese desktop wallpaper application, to deliver the ValleyRAT backdoor while making the infection look like a normal software installation. Researchers found a malicious installer that uses a modified version of QN Wallpaper, a legitimate Chinese desktop wallpaper application, to deliver the ValleyRAT backdoor while making the infection look like a normal software installation. The interesting part is how the attackers make the first stages look harmless. The installer can present itself as software associated with DingTalk, Google Chrome or Tencent Meeting, depending on the filename, while quietly deploying the modified wallpaper application in the background. That gives the victim something familiar to look at while the real work happens elsewhere. It’s a simple trick, but it removes one of the most obvious warning signs of a malware infection: the feeling that something unusual has just been installed. Kaspersky originally received one of the samples because a customer wanted it classified as adware. An initial look at the file suggested exactly that, but suspicious network activity changed the picture and led researchers to examine the sample more closely. They found that the advertising component didn’t actually perform its supposed job. Instead, it started an infection chain that eventually loaded ValleyRAT. “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.” reads Kaspersky’s report. “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.” That distinction matters because the attackers aren’t inventing a fake application from scratch. They’re abusing software that already looks legitimate and using its normal execution flow to load malicious code. The technique is DLL sideloading. In simple terms, the attacker places a malicious DLL where a legitimate program expects to find a library, allowing the trusted application to load the attacker’s code. Here, the relevant library is libcef.dll. QN Wallpaper and its companion process load that library when they start, giving the attackers a convenient place to execute their own code under the name of a legitimate application. The installer also creates persistence and disables Windows Defender through the DisableAntiSpyware registry key before launching QnWallpaper.exe. That combination makes the infection considerably more serious than ordinary adware. Once the malicious library runs, it checks whether the current user has administrator privileges. If necessary, it attempts to relaunch the process with elevated privileges before continuing with the next stage. The actual ValleyRAT payload sits encrypted inside the infection chain. Depending on which legitimate process loads the malicious library, the backdoor comes from either a separate PeLoader file or resources embedded in libcef.dll. The payloads use AES encryption and contain ValleyRAT as an encrypted DLL. Their configurations differ mainly in the command-and-control addresses they use, giving the operators more than one way to manage infected systems. ValleyRAT then starts behaving like the backdoor it actually is. It reads its configuration, connects to its command-and-control infrastructure and prepares a range of functions that give an attacker control over the compromised machine. The malware can collect keystrokes and clipboard contents, monitor the active window and gather detailed information about the infected system. That includes the hostname, IP addresses, Windows version, CPU information, available disk space, graphics adapter, language settings and other system details. “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.” continues the report. “All collected data is saved to a file on disk.” The operator can also order the backdoor to take screenshots, reboot or shut down the machine, wipe logs, change its command-and-control addresses and download additional modules. ValleyRAT can retrieve those modules from either its own C2 infrastructure or a third-party address. That last capability gives the attackers room to change what the malware does after the initial infection. They don’t need to put every capability into the first payload if they can download new components later. The malware also takes steps to make itself harder to remove. Depending on its configuration, it can inject code into svchost.exe so that the backdoor restarts if someone stops it. It can also mark its own process as critical, meaning that terminating it can trigger a system crash. That’s not subtle, but it’s effective. The malware is essentially telling the defender that killing the process isn’t supposed to be a clean operation. Kaspersky says ValleyRAT can detect security and traffic-analysis tools, while the campaign has been detected over 100,000 times in 2026, affecting more than 1,500 users, mainly in China and India. The activity is linked to Silver Fox, focused on both espionage and financial gain. In July 2026, Cato CTRL documented a SilverFox campaign targeting a Japanese industrial manufacturer. The attack chain adds two previously undocumented DLL-sideloading hosts, two kernel drivers not previously associated with SilverFox, and a dual-layer recovery architecture that keeps ValleyRAT running even if defenders terminate individual components. That broader activity puts the Kaspersky finding into perspective. The adware campaign isn’t an isolated curiosity. It fits a larger pattern in which Silver Fox uses legitimate software, familiar brands and trusted execution paths to get malicious code onto Windows systems and keep it there. For defenders, blocking a known ValleyRAT file is not enough because the real risk is how the malware gets executed. A legitimate-looking application, signed component or familiar installer can become part of a malicious chain. Antivirus exclusions can make the problem worse by creating blind spots. “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.” concludes the report. “The attackers exploited a well-known adware application to run the backdoor under the guise of a signed process, which complicates detection.” Kaspersky recommends clear rules for third-party software, security awareness and avoiding suspicious applications or exclusions simply because a program asks for them. The malware does not need to look dangerous; it only needs to look legitimate enough that nobody questions why an ordinary application suddenly behaves like a backdoor. Follow me on Twitter: @securityaffairs and Facebook and Mastodon Pierluigi Paganini (SecurityAffairs – hacking, newsletter)
A new ClickFix variant dubbed TerminalFix uses fake Cloudflare CAPTCHA prompts on compromised websites to trick victims into executing malicious PowerShell commands in Windows Terminal. Unlike typical ClickFix attacks that often lead to infostealer malware infections, this campaign uses a multi-stage intrusion chain that ultimately gives attackers a reverse tunnel into the victim’s internal network. TerminalFix differs from normal ClickFix attacks in that it directs users to Windows Terminal or PowerShell, which enables successful execution of more complex, multi-line scripts. Microsoft discovered the attacks in the wild but did not observe hands-on activity. However, the researchers warn that access obtained this way could be leveraged for lateral movement, privilege escalation, credential theft, disabling security tools, data exfiltration, or deploying ransomware.
Microsoft is investigating a widespread service issue causing authentication issues, connection problems, email delays and failures, and various other issues for Microsoft 365 customers. It first acknowledged this incident (tracked under EX1464935 in the admin center) at 5:30 PM UTC, when it began investigating a stream of reports from users on social media regarding multiple issues affecting Exchange Online. However, while Exchange Online is the most impacted service, Microsoft revealed in a new incident report (MO1465074) that this outage also impacts multiple other Microsoft 365 services, including OneDrive for Business and SharePoint Online, Microsoft Teams, Microsoft Purview, and Microsoft Defender XDR. According to outage tracking service Downdetector, tens of thousands of Outlook and Microsoft 365 users are affected and experiencing issues receiving emails via Outlook and accessing Microsoft cloud services.
The researchers discovered Fire Ant's new tactic after finding an active GRE (Generic Routing Encapsulation) tunnel interface on a Cisco IOS XR router that could not be explained by a running configuration or commit history. According to incident response company Sygnia, the threat actor switched from targeting VMware hypervisors to compromising Cisco routers, TACACS authentication servers, and Linux management hosts. The researchers discovered Fire Ant's new tactic after finding on a Cisco IOS XR router an active GRE (Generic Routing Encapsulation) tunnel interface that could not be explained by a running configuration or commit history. Further analysis revealed that Fire Ant had deployed custom malware on the devices, enabling persistence through a fake system service that ran the implant only during alternating hours.
File servers remain a critical part of many IT environments, but managing access securely can become complex as permissions accumulate. tenfold Software outlines five best practices for simplifying file server administration and maintaining least-privilege access.
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)
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