UserAddedToSensitiveGroup.md

User added to sensitive group

Query Information

MITRE ATT&CK Technique(s)

Technique ID	Title	Link
T1078.002	Valid Accounts: Domain Accounts	https://attack.mitre.org/techniques/T1078/002

Description

In order to gain high priviliges an adversary can add themselfs to groups with high priviliges. Those priviliges allow the adversary to perform almost every action in your environment. This query is currently only used to detect three different sensitive groups, however other (custom) groups can be added to the list with sensitive groups.

A false positive would be a account that is legitimately added to the sensitive group.

Risk

A attacker has added themself to a sensitive group and can perform priviliges actions.

References

• https://learn.microsoft.com/en-us/defender-for-identity/entity-tags#sensitive-entities

Defender XDR

let SensitiveGroups = dynamic(['Domain Admins', 'Enterprise Admins', 'Exchange Admins']); // Add your sensitive groups to this list
IdentityDirectoryEvents
| where Timestamp > ago(30d)
| where ActionType == "Group Membership changed"
| extend Group = parse_json(AdditionalFields).['TO.GROUP']
| extend GroupAdditionInitiatedBy = parse_json(AdditionalFields).['ACTOR.ACCOUNT']
| project-reorder Group, GroupAdditionInitiatedBy
| where Group has_any (SensitiveGroups)

Sentinel

let SensitiveGroups = dynamic(['Domain Admins', 'Enterprise Admins', 'Exchange Admins']); // Add your sensitive groups to this list
IdentityDirectoryEvents
| where TimeGenerated > ago(30d)
| where ActionType == "Group Membership changed"
| extend Group = parse_json(AdditionalFields).['TO.GROUP']
| extend GroupAdditionInitiatedBy = parse_json(AdditionalFields).['ACTOR.ACCOUNT']
| project-reorder Group, GroupAdditionInitiatedBy
| where Group has_any (SensitiveGroups)