Sigma rule: Invoke-Obfuscation VAR+ Launcher - Security

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-17ba2fc66876, updated 2022-11-29T00:00:00.000Z.

Rule

Title
Invoke-Obfuscation VAR+ Launcher - Security
Status
test
Level
high
Author
Jonathan Cheong, oscd.community
Date
2020-10-15
Modified
2022-11-29
File
rules/windows/builtin/security/win_security_invoke_obfuscation_var_services_security.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects Obfuscated use of Environment Variables to execute PowerShell

Log source

product
windows
service
security
definition
The 'System Security Extension' audit subcategory need to be enabled to log the EID 4697

Detection

selection:
    EventID: 4697
    # ServiceFileName|re: 'cmd.{0,5}(?:\/c|\/r)(?:\s|)\"set\s[a-zA-Z]{3,6}.*(?:\{\d\}){1,}\\\"\s+?\-f(?:.*\)){1,}.*\"'
    # Example 1: C:\winDoWs\SySTeM32\cmd.Exe /C"SET NOtI=Invoke-Expression (New-Object Net.WebClient).DownloadString&& PowERshElL -NOl SET-iteM ( 'VAR' + 'i'+ 'A' + 'blE:Ao6' + 'I0') ( [TYpe](\"{2}{3}{0}{1}\"-F 'iRoN','mENT','e','nv') ) ; ${exECUtIONCOnTEXT}.\"IN`VO`KecOmMaND\".\"inVo`KES`crIPt\"( ( ( GEt-VAriAble ( 'a' + 'o6I0') -vaLU )::(\"{1}{4}{2}{3}{0}\" -f'e','gETenvIR','NtvaRIa','BL','ONme' ).Invoke(( \"{0}{1}\"-f'n','oti' ),( \"{0}{1}\" -f'pRoC','esS') )) )"
    # Example 2: cMD.exe /C "seT SlDb=Invoke-Expression (New-Object Net.WebClient).DownloadString&& pOWErShell .(( ^&(\"{1}{0}{2}{3}\" -f 'eT-vaR','G','iab','lE' ) (\"{0}{1}\" -f '*m','DR*' ) ).\"na`ME\"[3,11,2]-JOIN'' ) ( ( ^&(\"{0}{1}\" -f'g','CI' ) (\"{0}{1}\" -f 'ENV',':SlDb' ) ).\"VA`luE\" ) "
    ServiceFileName|contains|all:
        - 'cmd'
        - '"set'
        - '-f'
    ServiceFileName|contains:
        - '/c'
        - '/r'
condition: selection

False positives (as the rule lists them)

  • Unknown

Tags

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

MITRE ATT&CK ids this rule names

Related rules

References

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/builtin/security/win_security_invoke_obfuscation_var_services_security.yml

Sources and licences

  • SigmaHQ

    "Invoke-Obfuscation VAR+ Launcher - Security" by Jonathan Cheong, oscd.community (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/builtin/security/win_security_invoke_obfuscation_var_services_security.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: Invoke-Obfuscation VAR+ Launcher - Security",
entity page, dataset version ref-17ba2fc66876, updated 2022-11-29T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/dcf2db1f-f091-425b-a821-c05875b8925a (accessed 2026-11-03).
Underlying source: SigmaHQ rule dcf2db1f-f091-425b-a821-c05875b8925a, 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.