PUA - NirCmd Execution

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

Detects the use of NirCmd tool for command execution, which could be the result of legitimate administrative activity

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1569.002` System Services: Service Execution

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `1 of selection_org`

or:
Image|endswith: '\NirCmd.exe'
OriginalFileName: NirCmd.exe

Stage 2: `1 of selection_cmd`

or:
CommandLine|contains: ' execmd '
CommandLine|contains: ' runinteractive '
CommandLine|contains: '.exe script '
CommandLine|contains: '.exe shexec '

Stage 3: `all of combo_exec`

or:
CommandLine|contains: ' exec '
CommandLine|contains: ' exec2 '

Stage 4: `all of combo_exec_params`

or:
CommandLine|contains: ' hide '
CommandLine|contains: ' show '

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	`exec` corpus 2 (sigma 2) `exec2` `execmd` `hide` `runinteractive` `show` `.exe script` `.exe shexec`
`Image`	ends_with	`\NirCmd.exe`
`OriginalFileName`	eq	`NirCmd.exe` corpus 2 (sigma 2)

PUA - NirCmd Execution

MITRE ATT&CK coverage

Event coverage

Stages and Predicates

Stage 1: 1 of selection_org

Stage 2: 1 of selection_cmd

Stage 3: all of combo_exec

Stage 4: all of combo_exec_params

Indicators

Stage 1: `1 of selection_org`

Stage 2: `1 of selection_cmd`

Stage 3: `all of combo_exec`

Stage 4: `all of combo_exec_params`