Håkon Måløy aidefend-sf0033

Copilot for Word Hidden-Prompt Document Worm

A white-on-white JSON prompt inside a Word document survived formatting removal and influenced Copilot for Word. The proof of concept halved financial figures and copied the same hidden prompt into a newly generated document. Propagation is workflow-dependent: each hop requires the carrier document to enter another Copilot drafting or editing operation.

Mapped threat techniques

AML.T0104 Social Engineering
AML.T0051.001 LLM Prompt Injection: Indirect
AML.T0053 AI Agent Tool Invocation
AML.T0080.000 AI Agent Context Poisoning: Memory

Source

SourceHåkon Måløy · Copilot for Word document AI worm

Updated2026-08-25