PowerShell Using Memory Stream as Backing Store

This analytic detects suspicious PowerShell script execution that utilizes memory streams as a backing store, identified through EventCode 4104 (PowerShell Script Block Logging). It specifically looks for scripts that create new objects with 'IO.MemoryStream', a technique often employed to decompress and execute payloads directly in memory. This activity is significant as it indicates potential in-memory execution of malicious code, which can bypass traditional file-based detection mechanisms. If confirmed malicious, this technique could allow attackers to execute arbitrary code, maintain persistence, or escalate privileges without leaving traces on disk.