Name:Windows Indirect Command Execution Via pcalua id:3428ac18-a410-4823-816c-ce697d26f7a8 version:3 date:2024-09-30 author:Eric McGinnis, Splunk status:production type:TTP Description:The following analytic detects programs initiated by pcalua.exe, the Microsoft Windows Program Compatibility Assistant. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and parent process information. While pcalua.exe can start legitimate programs, it is significant because attackers may use it to bypass command line execution protections. If confirmed malicious, this activity could allow attackers to execute arbitrary commands, potentially leading to unauthorized actions, privilege escalation, or persistence within the environment. Data_source:
-Sysmon EventID 1
-Windows Event Log Security 4688
-CrowdStrike ProcessRollup2
search:| 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`
how_to_implement:The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process. known_false_positives:Some legacy applications may be run using pcalua.exe. Filter these results as needed. References: -https://twitter.com/KyleHanslovan/status/912659279806640128 -https://lolbas-project.github.io/lolbas/Binaries/Pcalua/ drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Living Off The Land' asset_type:Endpoint confidence:50 impact:50 message:The Program Compatability Assistant (pcalua.exe) launched the process $process_name$ mitre_attack_id: - 'T1202' observable: name:'dest' type:'Hostname' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'Processes.dest' - 'Processes.user' - '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' risk_score:25 security_domain:endpoint
