Microsoft 365 Anomalous Amount of Downloaded files

microsoft-365

Classification:

attack

Tactic:

TA0010-exfiltration

Technique:

T1567-exfiltration-over-web-service

Goal

Detect when a Microsoft 365 user downloads an anomalous amount of files. This could be an indicator of data exfilteration.

Strategy

Monitor Microsoft 365 audit logs to look for an anomalous amount of logs with an @evt.name value of @evt.name:FileDownloaded.

Triage and response

  1. Determine if the user {{@usr.email}} intended to download the files.
  2. If {{@usr.email}} is not responsible for file downloads, investigate {{@usr.email}} for anomalous activity. If necessary, initiate your company’s incident response (IR) process.