Detection: Windows AD Short Lived Server Object

Updated Date: 2024-05-21 ID: 193769d3-1e33-43a9-970e-ad4a88256cdb Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies the creation and quick deletion of a Domain Controller (DC) object within 30 seconds in an Active Directory environment, indicative of a potential DCShadow attack. This detection leverages Windows Security Event Codes 5137 and 5141, analyzing the duration between these events. This activity is significant as DCShadow allows attackers with privileged access to register a rogue DC, enabling unauthorized changes to AD objects, including credentials. If confirmed malicious, this could lead to unauthorized AD modifications, compromising the integrity and security of the entire domain.

Search

1 `wineventlog_security` EventCode=5137 OR EventCode=5141 ObjectDN="*CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration*" 
2| transaction ObjectDN startswith=(EventCode=5137) endswith=(EventCode=5141) 
3| eval short_lived=case((duration<30),"TRUE") 
4| search short_lived = TRUE 
5| stats values(ObjectDN) values(signature) values(EventCode) by _time, Computer, SubjectUserName 
6| `windows_ad_short_lived_server_object_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 5137	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`	N/A

Macros Used

Name	Value
wineventlog_security	`eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog:Security`
windows_ad_short_lived_server_object_filter	`search *`

windows_ad_short_lived_server_object_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
T1207	Rogue Domain Controller	Defense Evasion

KillChainPhase.EXPLOITAITON

NistCategory.DE_CM

Cis18Value.CIS_10

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, you ned to be ingesting Event codes 5137 and 5141. The Advanced Security Audit policy setting Audit Directory Services Changes within DS Access needs to be enabled. For these event codes to be generated, specific SACLs are required.

Known False Positives

Creating and deleting a server object within 30 seconds or less is unusual but not impossible in a production environment. Filter as needed.

Associated Analytic Story

Sneaky Active Directory Persistence Tricks

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Potential DCShadow Attack Detected on $Computer$	64	80	80

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: 2