Bulk M365 collection following anomalous device-code sign-in (unfamiliar client/location)
This rule detects potential cloud data exfiltration by identifying anomalous device-code authentication sign-ins followed by high-velocity file or mailbox access. It specifically monitors Microsoft 365 sign-in logs for device-code authentication sessions involving either an application (AppId) or a geographic location not seen in the user's previous 14-day baseline. If such a sign-in is immediately followed (within a 2-hour window) by a rapid burst of activity in SharePoint, OneDrive, or Exchange—defined by at least 20 operations at a rate of 5 or more events per minute—the rule flags the sequence as suspicious. This pattern is characteristic of attackers using stolen device-code tokens to programmatically mass-download or exfiltrate sensitive cloud data.
Microsoft Sentinel (KQL)
