Potential PowerShell Obfuscation Via Reversed Commands
A Sigma rule for process creation on Windows, by Teymur Kheirkhabarov (idea), Vasiliy Burov (rule), oscd.community, Tim Shelton.
high 2 ATT&CK techniques 2 programs it names
What it looks for
detection:
filter_main_encoded_keyword:
CommandLine|contains:
- ' -EncodedCommand '
- ' -enc '
selection_cli:
CommandLine|contains:
- 'hctac'
- 'kaerb'
- 'dnammoc'
- 'ekovn'
- 'eliFd'
- 'rahc'
- 'etirw'
- 'golon'
- 'tninon'
- 'eddih'
- 'tpircS'
- 'ssecorp'
- 'llehsrewop'
- 'esnopser'
- 'daolnwod'
- 'tneilCbeW'
- 'tneilc'
- 'ptth'
- 'elifotevas'
- '46esab'
- 'htaPpmeTteG'
- 'tcejbO'
- 'maerts'
- 'hcaerof'
- 'retupmoc'
selection_img:
- Image|endswith:
- '\powershell.exe'
- '\pwsh.exe'
- OriginalFileName:
- 'PowerShell.EXE'
- 'pwsh.dll'
condition: all of selection_* and not 1 of filter_main_*
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 Teymur Kheirkhabarov (idea), Vasiliy Burov (rule), oscd.community, Tim Shelton, 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.