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Description

The following analytic detects a suspicious computer account name change in Active Directory. It leverages Event ID 4781, which logs account name changes, to identify instances where a computer account name is changed to one that does not end with a $. This behavior is significant as it may indicate an attempt to exploit CVE-2021-42278 and CVE-2021-42287, which can lead to domain controller impersonation and privilege escalation. If confirmed malicious, this activity could allow an attacker to gain elevated privileges and potentially control the domain.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2024-05-17
  • Author: Mauricio Velazco, Splunk
  • ID: 35a61ed8-61c4-11ec-bc1e-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1078 Valid Accounts Defense Evasion, Persistence, Privilege Escalation, Initial Access
T1078.002 Domain Accounts Defense Evasion, Persistence, Privilege Escalation, Initial Access
Kill Chain Phase
  • Exploitation
  • Installation
  • Delivery
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


1
2
3
4



`wineventlog_security` EventCode=4781 OldTargetUserName="*$" NewTargetUserName!="*$" 
| table _time, Computer, Caller_User_Name, OldTargetUserName, NewTargetUserName 
| rename Computer as dest 
| `suspicious_computer_account_name_change_filter`

Macros

The SPL above uses the following Macros:

:information_source: suspicious_computer_account_name_change_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • EventCode
  • Computer
  • Caller_User_Name
  • OldTargetUserName
  • NewTargetUserName

How To Implement

To successfully implement this search, you need to be ingesting Windows event logs from your hosts. In addition, the Splunk Windows TA is needed.

Known False Positives

Renaming a computer account name to a name that not end with '$' is highly unsual and may not have any legitimate scenarios.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
70.0 100 70 A computer account $OldTargetUserName$ was renamed with a suspicious computer name on $dest$

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

Reference

Test Dataset

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 | version: 3