Aug 20, 2025 16:18:00

Microsoft didn't notify users that Copilot AI could bypass audit logs

A software engineer who used Microsoft's chatbot, Copilot, reported that he had successfully accessed files without leaving an audit log. The engineer reported this to Microsoft as a serious issue, but Microsoft reportedly only quietly fixed it without even notifying users.

Copilot Broke Your Audit Log, but Microsoft Won't Tell You - Pistachio Blog - Cybersecurity Awareness Training

https://pistachioapp.com/blog/copilot-broke-your-audit-log

The issue was reported by Zach Korman, chief technology officer of a security company.

Typically, when you request a file summary from Copilot, you'll receive a link to the file along with the summary, and the file's audit log will record that Copilot accessed it on your behalf.

However, if you explicitly ask the site not to provide a link to the file, the summary will be displayed, but no record of accessing the file will be kept.

The audit log records who accessed a file, and is useful for security purposes and can be used as evidence in court cases. Corman reported the issue to Microsoft, saying, 'I didn't discover this while searching for a vulnerability, but this issue occurred during normal use, so it's possible that other people have experienced the same thing.'

However, Microsoft did not respond promptly and instead quietly fixed the issue without Corman's knowledge.

When you report an issue to Microsoft, the status usually changes to 'Reproducing' and then to 'In Development' once work on a fix has begun. In Corman's case, the feature itself was fixed while it was still in the 'Reproducing' stage. When Corman asked for an explanation, the status was changed to 'In Development.'

Shortly after the report, Microsoft contacted us, saying, 'We will release a fix shortly, and you can freely disclose information the day after release.' Corman then asked, 'When will a CVE number be issued?' Microsoft responded, 'CVEs are assigned when customers need to take action to stay secure. In this case, the mitigation measures will be automatically pushed to Copilot, so users do not need to manually update their products, and therefore no CVE number will be assigned.'

'This response is completely contrary to Microsoft

policy ,' Corman said. 'If Microsoft doesn't assign a CVE, does that mean they won't notify customers?' Corman added. Furthermore, when Corman called Microsoft, they responded, 'There are no plans to make this public.' Corman added, 'This could cause significant damage to Microsoft customers.'

'Are companies that rely on Microsoft's audit logs to meet their technical security requirements not being told about this? There are many cases where companies rely on audit logs to detect, investigate, and respond to incidents. Audit logs are also used as key evidence in lawsuits. And now Microsoft is claiming that no one needs to know, even though the audit logs are likely incorrect. This raises new questions about whether Microsoft is hiding other facts as well,' Corman said.