Detects a non-Defender process writing mpam-fe*.exe to the Windows INetCache (INetCache) folder, which is a pattern used by BlueHammer to download WD signature updates via WinINet as a low-privilege user. The artifact mpam-fe[1].exe is produced by Windows HTTP caching and serves as a reliable indicator of this download method. The rule relies on Sysmon EventID 11 and 23 to capture targeted file write activity to INetCache and filters for TargetFilename patterns matching INetCache paths and mpam-fe*.exe, while excluding Defender-related executables and folders. The detection aggregates findings by host, destination, process image, and EventID, and is intended to be used with endpoint telemetry mapped to the CIM Endpoint data model. Full command-line and process lineage data from EDR should be ingested to enable accurate correlation with the update process. The analytic storyline references Windows Persistence Techniques and BlueHammer. Known false positives include legitimate system maintenance tools or security scanners that perform similar downloads; these should be suppressed when tools are verified. This rule is designed for Splunk environments with EDR integration to alert on suspicious Defender update activity initiated by non-Defender processes on Windows endpoints.