Detection: Windows AD Privileged Account SID History Addition

Updated Date: 2024-09-30 ID: 6b521149-b91c-43aa-ba97-c2cac59ec830 Author: Dean Luxton Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies when the SID of a privileged user is added to the SID History attribute of another user. It leverages Windows Security Event Codes 4742 and 4738, combined with identity lookups, to detect this activity. This behavior is significant as it may indicate an attempt to abuse SID history for unauthorized access across multiple domains. If confirmed malicious, this activity could allow an attacker to escalate privileges or maintain persistent access within the environment, posing a significant security risk.

 1`wineventlog_security` (EventCode=4742 OR EventCode=4738) NOT SidHistory IN ("%%1793", -) 
 2| rex field=SidHistory "(^%{
 3|^)(?P<SidHistory>.*?)(}$
 4|$)" 
 5| eval category="privileged" 
 6| lookup identity_lookup_expanded category, identity as SidHistory OUTPUT identity_tag as match 
 7| where isnotnull(match) 
 8| rename TargetSid as userSid 
 9| table _time action status host user userSid SidHistory Logon_ID src_user 
10| `windows_ad_privileged_account_sid_history_addition_filter`

Data Source

Name Platform Sourcetype Source
Windows Event Log Security 4738 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'
Windows Event Log Security 4742 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'

Macros Used

Name Value
wineventlog_security eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog:Security
windows_ad_privileged_account_sid_history_addition_filter search *
windows_ad_privileged_account_sid_history_addition_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
T1134.005 SID-History Injection Defense Evasion
T1134 Access Token Manipulation Privilege Escalation
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
Blue Mockingbird
FIN6

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

Ensure you have objectSid and the Down Level Logon Name DOMAIN\sAMACountName added to the identity field of your Asset and Identities lookup, along with the category of privileged for the applicable users. Ensure you are ingesting eventcodes 4742 and 4738. Two advanced audit policies Audit User Account Management and Audit Computer Account Management under Account Management are required to generate these event codes.

Known False Positives

Migration of privileged accounts.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
A Privileged User Account SID History Attribute was added to $userSid$ by $src_user$ 90 100 90
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