Detection: Windows DnsAdmins New Member Added

Updated Date: 2024-05-29 ID: 27e600aa-77f8-4614-bc80-2662a67e2f48 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the addition of a new member to the DnsAdmins group in Active Directory by leveraging Event ID 4732. This detection uses security event logs to identify changes to this high-privilege group. Monitoring this activity is crucial because members of the DnsAdmins group can manage the DNS service, often running on Domain Controllers, and potentially execute malicious code with SYSTEM privileges. If confirmed malicious, this activity could allow an attacker to escalate privileges and gain control over critical domain services, posing a significant security risk.

Search

1 `wineventlog_security` EventCode=4732 TargetUserName=DnsAdmins 
2| stats min(_time) as firstTime max(_time) as lastTime values(TargetUserName) as target_users_added values(user) as user by  dest src_user 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `windows_dnsadmins_new_member_added_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 4732	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`	N/A

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_dnsadmins_new_member_added_filter	`search *`

windows_dnsadmins_new_member_added_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1098	Account Manipulation	Persistence

KillChainPhase.EXPLOITAITON

KillChainPhase.INSTALLATION

NistCategory.DE_CM

Cis18Value.CIS_10

APT3

APT41

APT5

Dragonfly

FIN13

HAFNIUM

Kimsuky

Lazarus Group

Magic Hound

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

To successfully implement this search, Domain Controller events need to be ingested. The Advanced Security Audit policy setting Audit Security Group Management within Account Management needs to be enabled.

Known False Positives

New members can be added to the DnsAdmins group as part of legitimate administrative tasks. Filter as needed.

Associated Analytic Story

Active Directory Privilege Escalation

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A new member $user$ added to the DnsAdmins group by $src_user$	40	80	50

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Security`	`XmlWinEventLog`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 4