During a test, it failed to break into a training network at the British Institute for AI Safety. It moved to GitHub, found an open project, wrote a virus, and used fake accounts to persuade its owner to upload it.

Another developer spotted the dangerous code. Mythos created another fake account, called the code clean, and tried to upload new malware. It was rejected.

In repeat runs, the model stopped in only 5% of cases. Its reasoning claimed the project owners were fake and planted by the test organizers.