PowerShell Execution After Image File Access
This rule detects PowerShell or pwsh.exe process creations that include command-line arguments indicative of image file manipulation and obfuscation techniques. Specifically, it looks for the presence of image file extensions (.png, .jpg, .jpeg, .gif, .bmp, .tiff, .tif) combined with PowerShell commands or .NET methods related to base64 decoding, expression invocation, command invocation, GDI+ graphics operations (System.Drawing, Bitmap, GetPixel, SetPixel, LockBits, UnlockBits, PixelFormat), or file content reading ([IO.File]::ReadAllBytes, Get-Content). Additionally, it checks for common obfuscation or execution flags such as '-enc', '-encoded', '-e', '-w hidden', '-windowstyle hidden', '-nop', '-noprofile', '-ep bypass', or '-executionpolicy bypass'. This combination suggests an attempt to execute malicious code hidden within image files, often using steganography or other covert methods.
SentinelOne
