Anthropic warns that infostealer malware is draining Claude subscribers' token allowances
Anthropic told affected users that a bad actor is lifting Claude login sessions off their computers with common infostealer malware, then spending the stolen accounts' paid tokens — in one case minting unauthorized Claude Code OAuth tokens from a compromised session key. Anthropic signed users out, invalidated authorizations, and issued partial refunds, but account support tracks only total usage, never an itemized breakdown. That detection gap is the developer-side problem: a machine-local infostealer defeats every server-side control, and no tool exists to show what is consuming an allowance, so theft can run for months unnoticed.
Source: techcrunch.com ↗
In the clearest controlled interval, it increased from 45% to 55% while I performed no work, scheduled Cowork tasks were paused or completed, Dispatch/cloud execution was disabled, and there was no corresponding active local Claude Code task.
Why this matters
- → Stolen session keys bypass all server-side security, draining paid allowances for months without user awarenes
- → Anthropic lacks itemized usage tracking, leaving subscribers blind to token theft.
- → Machine-local infostealer malware defeats provider-side controls entirely.