Case copilot-audit-log-bypassModel & data leakUnited States
Microsoft 365 Copilot summarised files without writing audit log entries
Pistachio CTO Zack Korman found that asking Copilot to omit the reference link when summarising a file produced no audit record, letting insiders read documents without a trace. Microsoft fixed it on 17 August 2025.
MediumAttack on AIStatus: PatchedVerified case file
Open in the interactive mapCite this case
- Reported
- Aug 18, 2025
- Location
- United States
- Target
- Microsoft 365 Copilot enterprise customers
- Severity
- Medium
- Triggered by
- Zack Korman (Pistachio)
- Actor type
- Security researchers
- Reported loss
- None reported
- CVE
- None
What happened
Pistachio CTO Zack Korman found that asking Copilot to omit the reference link when summarising a file produced no audit record, letting insiders read documents without a trace. Microsoft fixed it on 17 August 2025.
Impact: Compliance and forensic logs may be incomplete for an unknown period
Who triggered it
Actor: Zack Korman (Pistachio)
Attribution: Reported to MSRC on 4 July 2025; researcher published after Microsoft declined to notify customers
Motive: Security research
How it happened
Attack vector: Prompt phrasing that suppressed the citation link also suppressed audit logging of file access
Root cause: Audit record generation tied to link rendering rather than to the underlying file read
Timeline
- Korman reports the flaw to MSRC
- Microsoft deploys the fix, rated important
- Public disclosure
Response
Microsoft fixed the logging gap silently without a CVE
Current status: Patched
Sources (open in a new tab)
Cite this case
Microsoft 365 Copilot summarised files without writing audit log entries. AI Threat Watch, case copilot-audit-log-bypass, Aug 18, 2025. https://aithreat.io/cases/copilot-audit-log-bypass/
Permanent link: https://aithreat.io/cases/copilot-audit-log-bypass/