Infostealers are draining Claude subscriptions through stolen sessions

Commodity infostealer malware is lifting Claude login sessions off developer machines and spending the token allowance behind them, according to TechCrunch, which documented at least four affected users.

Grant De Swardt's $200/month account burned through tokens between August 4 and 5 while he wasn't working. Anthropic signed users out, invalidated the stolen authorizations, and issued partial refunds. De Swardt got no warning email and a refund of £44.49. Anthropic declined to give him an itemized usage report.

That refusal is the part of this story that matters most. Itemized usage with timestamps is exactly what would let a subscriber notice their account was being spent at 3am from a machine they weren't touching. Without it, you find out when you hit a limit you shouldn't have hit, and your only move is asking support to take your word for it.

There's nothing exotic in the exploit itself. Session tokens sit on disk in the same places every other credential does, and infostealers have been vacuuming those directories for a decade. What changed is that the token now carries a per-month dollar value that resells cleanly. A stolen Claude session is worth real money to someone who wants frontier inference without paying for it, and unlike a stolen credit card it doesn't trigger a fraud alert.

Rotate your sessions on every machine that has ever run a coding agent, including the laptop you stopped using. Pull your usage timeline and look at hours you know you were asleep, since timing is the only signal available when itemization isn't on the table. And check whether your machine has been through an infostealer at all. These families grab browser cookies, SSH keys, and cloud credentials in the same pass, so the Claude session was almost certainly not the only thing taken.

A second fight over the same gap

Anthropic power users also filed a class action over subscription plan changes, arguing that rate-limit and quota shifts are a contract question, per The Verge. Different complaint, same root cause: a subscription with a metered resource behind it needs the accounting a metered service provides, and right now it doesn't have it.