The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the execution of PowerShell with arguments utilized to start a process on a remote endpoint by abusing the WinRM protocol. Specifically, this search looks for the abuse of the
Invoke-Command commandlet. Red Teams and adversaries alike may abuse WinRM for lateral movement and remote code execution.
- Type: TTP
Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Last Updated: 2022-03-22
- Author: Mauricio Velazco, Splunk
- ID: 7d4c618e-4716-11ec-951c-3e22fbd008af
Kill Chain Phase
- CIS 10
1 2 3 4 5 `powershell` EventCode=4104 (ScriptBlockText="*Invoke-Command*" AND ScriptBlockText="*-ComputerName*") | stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer user_id | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `remote_process_instantiation_via_winrm_and_powershell_script_block_filter`
The SPL above uses the following Macros:
remote_process_instantiation_via_winrm_and_powershell_script_block_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 instructions can be found https://docs.splunk.com/Documentation/UBA/188.8.131.52/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
Known False Positives
Administrators may leverage WinRM and
Invoke-Command to start a process on remote systems for system administration or automation use cases. This activity is usually limited to a small set of hosts or users. In certain environments, tuning may not be possible.
Associated Analytic Story
|45.0||90||50||A process was started on a remote endpoint from $Computer$ by abusing WinRM using PowerShell.exe|
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