The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify suspicious PowerShell execution. Script Block Logging captures the command sent to PowerShell, the full command to be executed. Upon enabling, logs will output to Windows event logs. Dependent upon volume, enable no critical endpoints or all.
This analytic identifies common Mimikatz functions that may be identified in the script block, including
mimikatz. This will catch the most basic use cases for Pass the Ticket, Pass the Hash and
During triage, review parallel processes using an EDR product or 4688 events. It will be important to understand the timeline of events around this activity. Review the entire logged PowerShell script block.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-02-24
- Author: Michael Haag, Splunk
- ID: 8148c29c-c952-11eb-9255-acde48001122
Kill Chain Phase
1 2 3 4 5 `powershell` EventCode=4104 ScriptBlockText IN (*mimikatz*, *-dumpcr*, *sekurlsa::pth*, *kerberos::ptt*, *kerberos::golden*) | stats count min(_time) as firstTime max(_time) as lastTime by Opcode Computer UserID EventCode ScriptBlockText | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `detect_mimikatz_with_powershell_script_block_logging_filter`
The SPL above uses the following Macros:
detect_mimikatz_with_powershell_script_block_logging_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 analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/220.127.116.11/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
Known False Positives
False positives should be limited as the commands being identifies are quite specific to EventCode 4104 and Mimikatz. Filter as needed.
Associated Analytic Story
|90.0||90||100||The following behavior was identified and typically related to MimiKatz being loaded within the context of PowerShell on $Computer$ by $UserID$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
source | version: 2