Permission Check Via Accesschk.EXE

Severity: medium
Author: Teymur Kheirkhabarov (idea), Mangatas Tondang, oscd.community, Nasreddine Bencherchali (Nextron Systems)
Source: upstream

Detects the usage of the "Accesschk" utility, an access and privilege audit tool developed by SysInternal and often being abused by attacker to verify process privileges

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1069.001` Permission Groups Discovery: Local Groups

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Description|contains: 'Reports effective permissions'
Image|endswith: '\accesschk.exe'
Image|endswith: '\accesschk64.exe'
OriginalFileName: accesschk.exe
Product|endswith: AccessChk

Stage 2: `all of selection_cli`

or:
CommandLine|contains: 'kwsu '
CommandLine|contains: 'qwsu '
CommandLine|contains: 'uwcqv '
CommandLine|contains: 'uwdqs '

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	`kwsu` `qwsu` `uwcqv` `uwdqs`
`Description`	match	`Reports effective permissions`
`Image`	ends_with	`\accesschk.exe` corpus 3 (sigma 3) `\accesschk64.exe` corpus 2 (sigma 2)
`OriginalFileName`	eq	`accesschk.exe`
`Product`	ends_with	`AccessChk`