Steganographic Payload Execution via Image File
This rule detects suspicious process creation events where `explorer.exe` (Windows Explorer) launches various scripting or utility executables (`powershell.exe`, `cmd.exe`, `wscript.exe`, `mshta.exe`, `rundll32.exe`, `regsvr32.exe`, `installutil.exe`, `wmic.exe`, `certutil.exe`, `msdt.exe`). The detection is specifically triggered when the command line of the launched process contains indicators of network communication (e.g., `http://`, `https://`, `iwr`, `invoke-webrequest`, `curl`, `wget`, `bitsadmin`, `downloadstring`, `downloadfile`), encoded commands (`-e` or `-encodedcommand` with base64-like strings), or UNC paths (`\\`). It also specifically looks for `certutil` being used with `-urlcache`, `-decode`, or `-f` flags. The rule includes exclusions for common legitimate activities such as downloads from `chocolatey.org`, `nuget.org`, `aka.ms`, `cmd.exe` launching a browser to a URL, and `certutil -hashfile` operations.
SentinelOne
