Hackers Using New QuirkyLoader Malware to Spread Agent Tesla, AsyncRAT and Snake Keylogger
Aug 21, 2025
Malware / Email Security
Cybersecurity researchers have disclosed details of a new malware loader called QuirkyLoader that's being used to deliver via email spam campaigns an array of next-stage payloads ranging from information stealers to remote access trojans since November 2024. Some of the notable malware families distributed using QuirkyLoader include Agent Tesla , AsyncRAT , Formbook , Masslogger , Remcos RAT , Rhadamanthys Stealer , and Snake Keylogger . IBM X-Force, which detailed the malware, said the attacks involve sending spam emails from both legitimate email service providers and a self-hosted email server. These emails feature a malicious archive, which contains a DLL, an encrypted payload, and a real executable. "The actor uses DLL side-loading, a technique where launching the legitimate executable also loads the malicious DLL," security researcher Raymond Joseph Alfonso said . "This DLL, in turn, loads, decrypts, and injects the final payload into its target process....