Forfiles.EXE Child Process Masquerading

Severity: high
Author: Nasreddine Bencherchali (Nextron Systems), Anish Bogati
Source: upstream

Detects the execution of "forfiles" from a non-default location, in order to potentially spawn a custom "cmd.exe" from the current working directory.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Evasion	`T1036` Masquerading

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `selection`

or:
ParentCommandLine|endswith: .exe
ParentCommandLine|endswith: '.exe"'
CommandLine|startswith: '/c echo "'
Image|endswith: '\cmd.exe'

Stage 2: `not 1 of filter_main_parent_not_sys`

or:
Image|contains: ':\Windows\SysWOW64\'
Image|contains: ':\Windows\System32\'
or:
ParentImage|contains: ':\Windows\SysWOW64\'
ParentImage|contains: ':\Windows\System32\'
Image|endswith: '\cmd.exe'
ParentImage|endswith: '\forfiles.exe'

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`	starts_with	`/c echo "`
`Image`	ends_with	`\cmd.exe` corpus 92 (sigma 92)
`Image`	match	`:\Windows\SysWOW64\` corpus 7 (sigma 7) `:\Windows\System32\` corpus 6 (sigma 6)
`ParentCommandLine`	ends_with	`.exe` `.exe"`
`ParentImage`	ends_with	`\forfiles.exe`
`ParentImage`	match	`:\Windows\SysWOW64\` corpus 2 (sigma 2) `:\Windows\System32\` corpus 2 (sigma 2)