Permission Misconfiguration Reconnaissance Via Findstr.EXE

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

Detects usage of findstr with the "EVERYONE" or "BUILTIN" keywords. This was seen being used in combination with "icacls" and other utilities to spot misconfigured files or folders permissions.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1552.006` Unsecured Credentials: Group Policy Preferences

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_findstr_img`

or:
Image|endswith: '\find.exe'
Image|endswith: '\findstr.exe'
OriginalFileName: FIND.EXE
OriginalFileName: FINDSTR.EXE

Stage 2: `all of selection_findstr_cli`

or:
CommandLine|contains: 'BUILTIN\'
CommandLine|contains: 'Everyone'
CommandLine|contains: "BUILTIN\\"
CommandLine|contains: "Everyone"

Stage 3: `selection_special`

CommandLine|contains: Everyone
CommandLine|contains: 'findstr '
CommandLine|contains: 'icacls '

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	`"BUILTIN\\"` `"Everyone"` `'BUILTIN\'` `'Everyone'` `Everyone` `findstr` `icacls`
`Image`	ends_with	`\find.exe` corpus 8 (sigma 8) `\findstr.exe` corpus 11 (sigma 11)
`OriginalFileName`	eq	`FIND.EXE` corpus 6 (sigma 6) `FINDSTR.EXE` corpus 10 (sigma 10)