The following analytic detects programs that have been started by pcalua.exe. pcalua.exe is the Microsoft Windows Program Compatability Assistant. While this tool can be used to start legitimate programs, it has been observed being used to evade protections on command line execution.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2022-04-05
- Author: Eric McGinnis, Splunk
- ID: 3428ac18-a410-4823-816c-ce697d26f7a8
Kill Chain Phase
- CIS 8
- CIS 10
1 2 3 4 5 6 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process="*pcalua* -a*" by Processes.dest Processes.user Processes.parent_process Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_path | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_indirect_command_execution_via_pcalua_filter`
The SPL above uses the following Macros:
windows_indirect_command_execution_via_pcalua_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 logs with the full process path in the process field of CIM's Process data model. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where pcalua.exe may be used.
Known False Positives
Some legacy applications may be run using pcalua.exe. Filter these results as needed.
Associated Analytic Story
|25.0||50||50||The Program Compatability Assistant (pcalua.exe) launched the process $process_name$|
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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