Warden Stealer Malware Targets Claude, Codex, Grok and Cursor to Steal AI Agent Data
Warden Stealer, a Rust malware-as-a-service, harvests tokens and prompts from Claude, Codex, Grok, and Cursor.
Warden Stealer, also tracked as CallbackBeaver, is a Rust malware-as-a-service infostealer advertised on Russian-language underground forums since August 2026. Version 1.9, announced on September 29, officially steals tokens, prompt histories, conversation databases, and MCP settings from Claude, Codex, Grok, and Cursor, in addition to browsers, crypto wallets, password managers, and VPN clients. Its loader rebuilds the payload in memory and injects it into explorer.exe, with heavy obfuscation and anti-VM checks. Researchers say it bypasses Chromium Application-Bound Encryption by locating v20 key material and calling CryptUnprotectMemory inside the browser, a method similar to Vidar and Remus.