Sigma rule: Potential PowerShell Obfuscation Using Character Join

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-4b697f121861, updated 2023-01-09T00:00:00.000Z.

Rule

Title
Potential PowerShell Obfuscation Using Character Join
Status
test
Level
low
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2023-01-09
File
rules/windows/powershell/powershell_script/posh_ps_susp_alias_obfscuation.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects specific techniques often seen used inside of PowerShell scripts to obfscuate Alias creation

Log source

product
windows
category
ps_script
definition
Requirements: Script Block Logging must be enabled

Detection

selection:
    # Example:
    #   Set-Alias -Name Y -Value (-join("Ne","w-O","bje","ct"))
    #   Set-Alias -Name X -Value (-join("Inv","oke","-","Exp","ression"))
    ScriptBlockText|contains|all:
        - '-Alias' # For both "New-Alias" and "Set-Alias"
        - ' -Value (-join('
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

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

MITRE ATT&CK ids this rule names

Related rules

References

  • Internal Research

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/powershell/powershell_script/posh_ps_susp_alias_obfscuation.yml

Sources and licences

  • SigmaHQ

    "Potential PowerShell Obfuscation Using Character Join" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/powershell/powershell_script/posh_ps_susp_alias_obfscuation.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Potential PowerShell Obfuscation Using Character Join",
entity page, dataset version ref-4b697f121861, updated 2023-01-09T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/e8314f79-564d-4f79-bc13-fbc0bf2660d8 (accessed 2026-11-03).
Underlying source: SigmaHQ rule e8314f79-564d-4f79-bc13-fbc0bf2660d8, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.