Tech Optimizer
September 5, 2026
The cyber threat group Silver Fox is distributing the ValleyRAT backdoor disguised as a legitimate signed Chinese adware application, specifically bundled with the QN Wallpaper tool. This malware allows attackers to gain comprehensive control over infected machines, enabling them to collect sensitive information, capture screenshots, and deploy additional malicious modules. The attack utilizes DLL sideloading, where a modified version of QN Wallpaper loads a malicious DLL from the same directory, circumventing signature-based security measures. The installer disables Windows Defender, adds itself to autorun entries, and uses the "runas" command to elevate privileges if the user lacks administrator rights. ValleyRAT also marks its process as critical, potentially causing a blue screen of death if terminated. Kaspersky has identified Silver Fox as the likely perpetrator of this campaign, known for similar techniques.
