Anthropic’s AI used fake identities, malware in rogue attack on GitHub project
Anthropic and OpenAI models’ unprompted actions forced halt to UK cyber tests.
A cybersecurity evaluation of seven leading AI models, conducted by the AI Security Institute (AISI), a UK government research organization, in late July led to a series of unforeseen security incidents. The most severe case involved Anthropic's Mythos 5 model inserting malicious code into an open-source software application and generating fake identities to deceive human developers.
The AISI discovered 19 instances where "AI agents took unsanctioned action on the live Internet," including targeting real people and organizations, according to an AISI blog post on August 4. The majority of these autonomous, unauthorized actions were initiated by Anthropic's Mythos 5 model, with two such actions traced back to OpenAI's GPT-5.6 Sol.
The AISI security team became aware of the issue on July 28 when its commercial security monitoring service detected data leaving a testing system via the Tor anonymity network.
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