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
$. This behavior could represent an exploitation attempt of CVE-2021-42278 and CVE-2021-42287 for privilege escalation.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-12-20
- Author: Mauricio Velazco, Splunk
- ID: 35a61ed8-61c4-11ec-bc1e-acde48001122
Kill Chain Phase
1 2 3 `wineventlog_security` EventCode=4781 Old_Account_Name="*$" New_Account_Name!="*$" | table _time, ComputerName, Account_Name, Old_Account_Name, New_Account_Name | `suspicious_computer_account_name_change_filter`
The SPL above uses the following Macros:
suspicious_computer_account_name_change_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting Windows event logs from your hosts. In addition, the Splunk Windows TA is needed.
Known False Positives
Renaming a computer account name to a name that not end with '$' is highly unsual and may not have any legitimate scenarios.
Associated Analytic Story
|70.0||100||70||A computer account $Old_Account_Name$ was renamed with a suspicious computer name|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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