Sigma rule: Invoke-Obfuscation VAR++ LAUNCHER OBFUSCATION - Security

Rule

Title

Invoke-Obfuscation VAR++ LAUNCHER OBFUSCATION - Security

Status

test

Level

high

Author

Timur Zinniatullin, oscd.community

Date

2020-10-13

Modified

2022-11-29

File

rules/windows/builtin/security/win_security_invoke_obfuscation_via_var_services_security.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects Obfuscated Powershell via VAR++ LAUNCHER

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: '(?i)&&set.*(\{\d\}){2,}\\\"\s+?\-f.*&&.*cmd.*\/c' # FPs with |\/r
    # Example 1: CMD /C"sET KUR=Invoke-Expression (New-Object Net.WebClient).DownloadString&&Set MxI=C:\wINDowS\sYsWow64\winDOWspoWERSheLl\V1.0\PowerShelL.EXe ${ExEcut`IoN`cON`TExT}.\"invo`kEcoMm`A`ND\".( \"{2}{1}{0}\" -f 'pt','EscRi','INvOk' ).Invoke( ( .( \"{0}{1}\" -f'D','IR' ) ( \"{0}{1}\"-f'ENV:kU','R')).\"vAl`Ue\" )&& CMD /C%mXI%"
    # Example 2: c:\WiNDOWS\sYSTEm32\CmD.exE /C "sEt DeJLz=Invoke-Expression (New-Object Net.WebClient).DownloadString&&set yBKM=PoWERShelL -noeX ^^^&(\"{2}{0}{1}\"-f '-ItE','m','seT') ( 'V' + 'a'+ 'RiAblE:z8J' +'U2' + 'l' ) ([TYpE]( \"{2}{3}{0}{1}\"-f 'e','NT','e','NViRONM' ) ) ; ^^^& ( ( [sTrIng]${VE`Rbo`SepReFER`Ence})[1,3] + 'X'-joIN'')( ( (.('gI') ('V' + 'a' + 'RIAbLe:z8j' + 'u2' +'l' ) ).vALUe::( \"{2}{5}{0}{1}{6}{4}{3}\" -f 'IRo','Nm','GETE','ABlE','I','nv','enTVAr').Invoke(( \"{0}{1}\"-f'd','ejLz' ),( \"{1}{2}{0}\"-f'cEss','P','RO') )) )&& c:\WiNDOWS\sYSTEm32\CmD.exE /C %ybkm%"
    ServiceFileName|contains|all:
        - '&&set'
        - 'cmd'
        - '/c'
        - '-f'
    ServiceFileName|contains:
        - '{0}'
        - '{1}'
        - '{2}'
        - '{3}'
        - '{4}'
        - '{5}'
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

• T1027
• T1059.001

Related rules

• 14bcba49-a428-42d9-b943-e2ce0f0f7ae6 (derived)

References

• https://github.com/SigmaHQ/sigma/issues/1009

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_via_var_services_security.yml