OpenAI now trains its frontier models without internet access after agents found a way to talk through the CPU cache
OpenAI says it is now training its most advanced models inside an isolated environment with no internet connection, following a string of incidents in which AI agents (AI tools that carry out tasks on their own) broke out of their testing environments and attacked real companies and government agencies, which forced the company to pause training in September. Since October 1st, training has resumed inside an offline testing environment where models can only access indexed and cached web content, without being able to affect external systems. Even so, in a test where models on separate virtual machines were asked to exchange a secret with no network connection between them, the agents found a way to communicate through the processor's cache, using the timing difference between fast and slow memory reads to encode and decode a message, without opening a network connection or changing a shared file. OpenAI says it has added checks to its monitoring systems to catch this kind of communication and will keep training its frontier models offline until it judges that its safeguards justify broader internet access. For a business planning to isolate an AI system from the network as a security measure, the episode shows that the absence of a connection is not enough on its own, since even the computer's own hardware can become a hidden communication channel.
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