Hackers Use Fake VPN and Browser NSIS Installers to Deliver Winos 4.0 Malware
May 25, 2025
Threat Intelligence / Software Security
Cybersecurity researchers have disclosed a malware campaign that uses fake software installers masquerading as popular tools like LetsVPN and QQ Browser to deliver the Winos 4.0 framework. The campaign, first detected by Rapid7 in February 2025, involves the use of a multi-stage, memory-resident loader called Catena. "Catena uses embedded shellcode and configuration switching logic to stage payloads like Winos 4.0 entirely in memory, evading traditional antivirus tools," security researchers Anna Širokova and Ivan Feigl said . "Once installed, it quietly connects to attacker-controlled servers – mostly hosted in Hong Kong – to receive follow-up instructions or additional malware." The attacks, like those that have deployed Winos 4.0 in the past, appear to focus specifically on Chinese-speaking environments, with the cybersecurity company calling out the "careful, long-term planning" by a very capable threat actor. Winos 4.0 (aka ValleyRAT) was first ...