security
Commodity malware steals authenticated sessions, letting thieves freeload on victims' paid usage
Rather than paying for their own Claude usage, crims are using malware to steal access to other people's accounts. Aware of this issue, Anthropic has signed at least one affected user out and removed the saved payment method to stop stolen sessions being abused. According to an email shared by Reddit user WorriedAssociate7029, who sent a copy to The Register, Anthropic has been keeping an eye on a threat actor using infostealer malware to hijack Claude login details, session cookies, and other info needed to subvert multifactor authentication on user accounts. Once obtained, the miscreant is using the stolen information to use premium Claude services without having to pay the bill themselves.Fortunately for WorriedAssociate7029, Anthropic logged the user out of their account and deleted their stored payment method because it had detected evidence of attempted fraud.
“A few days ago, my social media accounts were hacked,” WorriedAssociate said, adding that they'd managed to track the malware down with the help of Claude Opus 5 Max and, they believe, cleaned the system. “But last night I received this email from Anthropic warning me of an attempt to steal tokens via the API.”
