Anthropic warned users over the weekend that a threat actor is using widely available infostealer malware to hijack active Claude login sessions from infected computers, then using those sessions to run up victims' paid usage without ever needing a password or a two-factor code.
The company said it identified six malware families in the campaign: Vidar, LummaC2, StealC, RedLine and Acreed on Windows, and Atomic Stealer, known as AMOS, on a smaller number of macOS machines. None are novel or bespoke. All are commodity stealers sold or rented on criminal dark web marketplaces, and all work the same basic way - harvesting locally stored browser credentials, autofill data and authentication cook...