The Malware Did Not Need Anyone's Password, and That Is the Whole Point

Which means the Claude accounts are not the story. They are a symptom that turned up because somebody noticed unusual usage on a metered product. If a machine gave up its Claude session, it gave up every other session in the same browser at the same moment: email, bank, cloud storage, work systems.

What the affected person actually has to do

Assume the machine is the problem, not the account.

Signing out of Claude everywhere invalidates the stolen Claude token. It does nothing about the malware that took it, which is still on the computer, still running, and will take the next token as soon as one is issued. Changing the password on a compromised machine hands the attacker the new password.

The order that works is: clean or rebuild the machine first, then change credentials from a device you trust, then revoke sessions everywhere. Doing those in the wrong order is a common and expensive mistake, and it feels like progress while achieving nothing.

For anyone who wants the honest version of the risk: an infostealer on a personal computer is a full compromise of everything that computer was signed into. Treat it that way rather than triaging one service at a time.

What this asks of the companies

Something more than sign-outs and refunds, eventually.

Session tokens have been the soft centre of web authentication for a decade, and the defences exist. Binding a session to a device, shortening its life for sensitive actions, watching for a session that suddenly appears from a different network and behaves differently: none of that is exotic. It is friction, and friction loses arguments to convenience until an incident makes the case.

The pattern is familiar from the other direction too. An automated attacker moving fast through a system that trusted a credential is what we picked apart in the lessons from an agent driven attack. Different mechanism, same underlying assumption: that whoever holds the token is who they say they are.

Anthropic's disclosure is the useful part here, and it deserves saying plainly. A company that says a bad actor got in through customers' own machines, names what it is doing about it, and refunds the charges is a company telling you something it could have quietly absorbed instead.