Suspicious Reconnaissance Activity Using Get-LocalGroupMember Cmdlet

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

Detects suspicious reconnaissance command line activity on Windows systems using the PowerShell Get-LocalGroupMember Cmdlet

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1087.001` Account Discovery: Local Account

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation
Security-Auditing	4688	A new process has been created.

Stages and Predicates

Stage 1: `all of selection_cmdlet`

CommandLine|contains: 'Get-LocalGroupMember '

Stage 2: `all of selection_group`

or:
CommandLine|contains: ' administrateur'
CommandLine|contains: ' administrator'
CommandLine|contains: 'Exchange Trusted Subsystem'
CommandLine|contains: 'Remote Desktop Users'
CommandLine|contains: 'Usuarios de escritorio remoto'
CommandLine|contains: 'Utilisateurs du Bureau à distance'
CommandLine|contains: 'domain admins'
CommandLine|contains: 'enterprise admins'

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	`administrateur` corpus 3 (sigma 3) `administrator` corpus 2 (sigma 2) `Exchange Trusted Subsystem` corpus 2 (sigma 2) `Get-LocalGroupMember` `Remote Desktop Users` corpus 3 (sigma 3) `Usuarios de escritorio remoto` corpus 3 (sigma 3) `Utilisateurs du Bureau à distance` corpus 3 (sigma 3) `domain admins` corpus 2 (sigma 2) `enterprise admins` corpus 2 (sigma 2)