This rule detects potential sideloading of the "mpclient.dll" file by Windows Defender's processes, specifically "MpCmdRun.exe" and "NisSrv.exe", when these processes access the DLL from locations outside their usual directories. By monitoring the loading of images and filtering out the common legitimate paths where these processes normally operate, the rule helps in identifying potential instances where an attacker might misuse the Windows Defender components for malicious purposes. The detection logic checks if the image ending with '\mpclient.dll' is called from either of the specified Defender processes, while ensuring the paths do not correspond to its default locations. As such, it addresses the risk of DLL sideloading attacks that exploit trusted processes to run malicious code without detection. Given the context of its operation, the rule is particularly relevant against threats utilizing techniques like LoadLibrary and similar API calls, which are common in attack behaviors aimed at evading detection by leveraging legitimate applications.