Dissecting CrashFix: KongTuke's New Toy | Huntress

In January 2026, Huntress Senior Security Operations Analyst Tanner Filip observed threat actors using a malicious browser extension to display a fake security warning, claiming the browser had “stopped abnormally” and prompting users to run a “scan” to remediate the threats. Our analysis revealed this campaign is the work of KongTuke, a threat actor we have been tracking since the beginning of 2025. In this latest operation, we identified several new developments: a malicious browser extension called NexShield that impersonates the legitimate uBlock Origin Lite ad blocker, a new ClickFix variant we have dubbed “CrashFix” that intentionally crashes the browser then baits users into running malicious commands, and ModeloRAT, a previously undocumented Python RAT reserved exclusively for domain-joined hosts.