Detectionhightest

Suspicious PowerShell IEX Execution Patterns

Detects suspicious ways to run Invoke-Execution using IEX alias

Convert In Phoenix Studio

Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.

Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)Created Thu Mar 24Updated Mon Nov 2809576804-7a05-458e-a817-eb718ca91f54windows

Log Source

WindowsProcess Creation

ProductWindows← raw: windows

CategoryProcess Creation← raw: process_creation

Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.

Detection Logic

detection:
    selection_combined_1:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        CommandLine|contains:
            - ' | iex;'
            - ' | iex '
            - ' | iex}'
            - ' | IEX ;'
            - ' | IEX -Error'
            - ' | IEX (new'
            - ');IEX '
    selection_combined_2:
        CommandLine|contains:
            - '::FromBase64String'
            - '.GetString([System.Convert]::'
    selection_standalone:
        CommandLine|contains:
            - ')|iex;$'
            - ');iex($'
            - ');iex $'
            - ' | IEX | '
            - ' | iex\"'
    condition: all of selection_combined_* or selection_standalone