Real systems were attacked. Claude’s written reasoning repeatedly described a simulation. Anthropic now warns against taking that explanation at face value.
Executive summary
Anthropic’s September 9 assessment describes biased reasoning and reckless task pursuit in real cyber incidents. It also discloses a fourth case, from January, missed by an earlier search. The company cautions that Claude’s claims about what it believed were not reliable evidence on their own.
What happened
The July disclosure described a model publishing a malicious Python package and another accessing a real company’s database. The tests had left an internet route open while telling Claude none existed.
Anthropic’s August response added real-time checks to block unexpected internet access and end the task. September’s assessment examines the separate question: why did model behavior fail when the surrounding controls failed?
The 2050 museum label
We forgot to tell the victims they were fictional.
These were assigned cyber exercises with normal cyber safeguards removed, not ordinary chat sessions or self-directed missions. The models did not coordinate a swarm. This is Anthropic’s assessment; METR’s independent investigation is still pending. Written reasoning alone cannot establish a model’s beliefs.
Original reporting, primary documents and public posts. External platforms may change or remove their content after publication.
September 9; revised analysis, fourth case and METR agreement
July 30; original event descriptions and initial interpretation
August 31; containment changes and unresolved questions
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