Suspicious RunAs-Like Flag Combination

Severity: medium
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects suspicious command line flags that let the user set a target user and command as e.g. seen in PsExec-like tools

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_user`

or:
CommandLine|contains: ' --system '
CommandLine|contains: ' --user system '
CommandLine|contains: ' -u ''NT'
CommandLine|contains: ' -u NT'
CommandLine|contains: ' -u "NT'
CommandLine|contains: ' -u administrator '
CommandLine|contains: ' -u system '

Stage 2: `all of selection_command`

or:
CommandLine|contains: ' --command cmd'
CommandLine|contains: ' --command powershell'
CommandLine|contains: ' -c "cmd'
CommandLine|contains: ' -c "powershell'
CommandLine|contains: ' -c cmd'
CommandLine|contains: ' -c cscript'
CommandLine|contains: ' -c powershell'
CommandLine|contains: ' -c whoami'
CommandLine|contains: ' -c wscript'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`--command cmd` `--command powershell` `--system` `--user system` `-c "cmd` `-c "powershell` `-c cmd` `-c cscript` `-c powershell` `-c whoami` `-c wscript` `-u "NT` `-u 'NT` `-u NT` `-u administrator` `-u system`