Anthropic Locks Out Claude Users Following Infostealer Malware Compromises

Anthropic has begun locking users out of their Claude AI accounts after detecting that login sessions were compromised by infostealer malware. The malware, including Vidar, Lumma (LummaC2), StealC, RedLine, Acreed on Windows, and Atomic Stealer (AMOS) on some Macs, typically arrives via unofficial downloads or malicious apps, stealing saved passwords and login cookies. Users are advised to scan for and remove malware, then reset passwords and enable 2FA.