Malicious File Uploaded to SharePoint for Taint

This rule detects the upload of a malicious executable file (identified by the 'MZ' header) to a SharePoint server via the REST API endpoint for folder manipulation. Specifically, it looks for HTTP POST requests to URIs containing '/_api/web/getfolderbyserverrelativeurl' with file data that starts with 'MZ'. This indicates an attempt to upload an executable file, potentially for lateral movement or further compromise within a SharePoint environment.