ACR Stealer, an infostealer active since 2024, is being distributed through ClickFix lures that trick users into pasting malicious commands into Windows' Run dialog, requiring no vulnerability or exploit to succeed. Once executed, the malware uses two delivery chains — one file-based and one nearly entirely in-memory — to steal browser passwords, session tokens, and Microsoft 365 documents, with techniques including payload concealment inside JPEG pixels and blockchain-based command-and-control infrastructure. Defenders are advised to block the paste-and-run vector via Group Policy, apply application control rules, revoke (not just rotate) compromised tokens, and hunt for indicators such as rundll32.exe making unexplained network connections or scheduled tasks disguised as software updates.
