Exchange Web Services Remote Email Harvesting
This rule detects potential email harvesting attempts via Exchange Web Services (EWS). It specifically looks for HTTP requests to the '/EWS/Exchange.asmx' endpoint containing 'FindItem' in the client body, indicating an attempt to enumerate or search for items (like emails) within mailboxes. A threshold is applied to prevent excessive alerts from legitimate, but frequent, EWS activity.
Suricata

