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Description

As part of the sAMAccountName Spoofing (CVE-2021-42278) and Domain Controller Impersonation (CVE-2021-42287) exploitation chain, adversaries need to create a new computer account name and rename it to match the name of a domain controller account without the ending '$'. In Windows Active Directory environments, computer account names always end with $. This analytic leverages Event Id 4781, The name of an account was changed, to identify a computer account rename event with a suspicious name that does not terminate with $. This behavior could represent an exploitation attempt of CVE-2021-42278 and CVE-2021-42287 for privilege escalation.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-12-20
  • Author: Mauricio Velazco, Splunk
  • ID: 35a61ed8-61c4-11ec-bc1e-acde48001122

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
`wineventlog_security` EventCode=4781 Old_Account_Name="*$" New_Account_Name!="*$" 
| table _time, ComputerName, Account_Name, Old_Account_Name, New_Account_Name 
| `suspicious_computer_account_name_change_filter`

Associated Analytic Story

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.

Required field

  • _time
  • EventCode
  • ComputerName
  • Account_Name
  • Old_Account_Name
  • New_Account_Name

Kill Chain Phase

  • Privilege Escalation

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.

RBA

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

CVE

ID Summary CVSS
CVE-2021-42287 Active Directory Domain Services Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-42278, CVE-2021-42282, CVE-2021-42291. 6.5
CVE-2021-42278 Active Directory Domain Services Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-42282, CVE-2021-42287, CVE-2021-42291. 6.5

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

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