Grok Has Been Leaking User Data Since June
Researchers at security firm Adversa have demonstrated an attack that forces Grok, xAI's AI assistant, to steal user chat histories and personal information, according to Ars Technica. At the time of publication, the attack still worked. xAI was told about it in June.
The technique is a variant of prompt injection (a method of hiding malicious instructions inside content an AI is asked to read, so the AI follows the attacker's commands instead of the user's). What makes this one different is the encryption.
Normally, AI systems are built with guardrails (filters that detect suspicious instructions and block them). Researcher Rony Utevsky found that encrypting the harmful instruction bypasses those filters entirely. A malicious webpage hosts the encrypted command, a decryption key, and plaintext instructions telling Grok how to decode it. When a user asks Grok to summarise the page, it reads the decryption instructions, decodes the command, and follows it without warning.
This is the same structural problem as a related Microsoft 365 Copilot attack disclosed earlier this week. The root issue is that AI models cannot reliably tell the difference between content they are reading and instructions they are meant to follow — the way it cannot distinguish a letter from a rulebook.
Guardrails are the current fix, and as this week has shown twice, they are not enough.
If you use Grok to summarise web content or emails, stop doing that until xAI confirms a fix is in place.
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