Organizations/researcher

Simon Willison

Independent developer and writer who named prompt injection.

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Jun 16, 2025
Simon Willison frames the 'lethal trifecta' of private data, untrusted content and exfiltration
DefenseFrameworkSimon Willison

Simon Willison argues that an agent becomes exploitable for data theft when it combines access to private data, exposure to untrusted content, and the ability to communicate externally. He advises users to avoid combining all three, points developers to design-pattern mitigations, and argues that guardrails catching most attacks are inadequate in a security setting.