Whoami.EXE Execution With Output Option

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

Detects the execution of "whoami.exe" with the "/FO" flag to choose CSV as output format or with redirection options to export the results to a file for later use.

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1033` System Owner/User Discovery

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_main_img`

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

Stage 2: `all of selection_main_cli`

or:
CommandLine|contains: ' -FO CSV'
CommandLine|contains: ' /FO CSV'

Stage 3: `selection_special`

CommandLine|contains: 'whoami*>'

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	`-FO CSV` `/FO CSV` `whoami*>`
`Image`	ends_with	`\whoami.exe` corpus 18 (sigma 18)
`OriginalFileName`	eq	`whoami.exe` corpus 9 (sigma 9)