Microsoft Copilot reveals secret input that allowed it to be hacked
Secret parameter allowed hackers to steal passwords when a target clicked on a link.
Researchers from security firm Varonis discovered a critical vulnerability in Microsoft 365 Copilot Enterprise by asking the AI assistant itself. Rather than using traditional reverse engineering methods, they posed questions to Copilot about the guardrails requiring user confirmation before executing powerful commands. The AI assistant refused to comply, but as researchers continued to probe, it eventually revealed a trade secret: an undocumented prompt parameter that bypassed the need for user consent.
By asking about auto-execution, URL structures, and the effects of preloaded input, the researchers pieced together information about the complex safety mechanism. This revelation marks a rare instance where attackers successfully forced a frontier AI model to disclose sensitive data without user confirmation.
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