Cybercriminals Deploy CORNFLAKE.V3 Backdoor via ClickFix Tactic and Fake CAPTCHA Pages
Aug 21, 2025
Malware / Cryptocurrency
Threat actors have been observed leveraging the deceptive social engineering tactic known as ClickFix to deploy a versatile backdoor codenamed CORNFLAKE.V3. Google-owned Mandiant described the activity, which it tracks as UNC5518, as part of an access-as-a-service scheme that employs fake CAPTCHA pages as lures to trick users into providing initial access to their systems, which is then monetized by other threat groups. "The initial infection vector, dubbed ClickFix, involves luring users on compromised websites to copy a malicious PowerShell script and execute it via the Windows Run dialog box," Google said in a report published today. The access provided by UNC5518 is assessed to be leveraged by at least two different hacking groups, UNC5774 and UNC4108, to initiate a multi-stage infection process and drop additional payloads - UNC5774, another financially motivated group that delivers CORNFLAKE as a way to deploy various subsequent payloads UNC4108, a threat act...