Windows AMSI Related Registry Tampering Via CommandLine
A Sigma rule for process creation on Windows, by Swachchhanda Shrawan Poudel (Nextron Systems).
high 1 ATT&CK technique 3 programs it names
What it looks for
detection:
selection_key:
CommandLine|contains|all:
- '\Software\Microsoft\Windows Script\Settings'
- 'AmsiEnable'
selection_powershell_cmd:
CommandLine|contains:
- 'Set-ItemProperty'
- 'New-ItemProperty'
- 'sp '
selection_powershell_img:
- Image|endswith:
- '\powershell.exe'
- '\pwsh.exe'
- OriginalFileName:
- 'PowerShell.EXE'
- 'pwsh.dll'
selection_reg_cmd:
CommandLine|contains: 'add'
selection_reg_img:
- Image|endswith: '\reg.exe'
- OriginalFileName: 'reg.exe'
condition: selection_key and (all of selection_powershell_* or all of selection_reg_*)
The rule’s detection, its selections and fields in order of name. The whole rule, with its references and false positives, is on SigmaHQ, by Swachchhanda Shrawan Poudel (Nextron Systems), under the Detection Rule License 1.1. CmdID evaluates it on a command line alone: a test on what a command line cannot show, such as the parent process or the user, is not met.
None of the everyday examples and documented commands on CmdID’s program pages trips it. To see whether a command line does, paste it into CmdID.
Programs and files it names
ATT&CK
T1685Disable or Modify Tools