O365 OneDrive Anonymous File Accessed

Google SecOps@GoogleSecOps

•updated Apr 1, 2025•0•28

This rule detects when anonymous links are used to access files from OneDrive. While not always malicious, some organizations prohibit anonymous links due to data leakage risks. The rule specifically looks for 'USER_RESOURCE_ACCESS' events with 'FileAccessed' product event type from Office 365, where the principal user ID indicates an anonymous access (e.g., 'urn:spo:anon#' or 'anonymous').