The rule identifies suspicious file creation events associated with the Microsoft Exchange Server Unified Messaging (UM) service. It targets activity indicative of exploitation of the vulnerability CVE-2021-26858. The detection rule is designed to trigger alerts on specific file types (.php, .jsp, .js, .aspx, .asmx, .asax, .cfm, .shtml) being created in particular directories related to Microsoft Exchange. This includes paths under 'inetpub' and the 'HttpProxy' directories of the Exchange Server. Positive detections should be referred to established Microsoft baselines for context, and users are advised to patch their systems as a primary mitigation step, although this may not remediate already compromised systems. The rule operates on various indices for endpoint logs and requires attribution to multiple data sources, including Winlogbeat and Microsoft Defender for Endpoint. False positives can generally arise from normal operations during initial software installations but can be mitigated through careful tuning and monitoring.