The following analytic identifies msiexec.exe with http in the command-line. This procedure will utilize msiexec.exe to download a remote file and load it. During triage, review parallel processes and capture any artifacts on disk for review.
- Type: TTP
- Product: Splunk Behavioral Analytics
- Datamodel: Endpoint_Processes
- Last Updated: 2022-08-31
- Author: Michael Haag, Splunk
- ID: 92cbbf0f-9a6b-4e9d-8c35-cc9244a4e3d5
Kill Chain Phase
1 2 3 4 5 6 | from read_ssa_enriched_events() | eval timestamp=parse_long(ucast(map_get(input_event, "_time"), "string", null)), cmd_line=lower(ucast(map_get(input_event, "process"), "string", null)), process_name=lower(ucast(map_get(input_event, "process_name"), "string", null)), process_path=ucast(map_get(input_event, "process_path"), "string", null), parent_process_name=ucast(map_get(input_event, "parent_process_name"), "string", null), event_id=ucast(map_get(input_event, "event_id"), "string", null) | where cmd_line IS NOT NULL AND process_name IS NOT NULL AND process_name="msiexec.exe" AND (like (cmd_line, "%http://%") OR like (cmd_line, "%https://%")) | eval start_time=timestamp, end_time=timestamp, entities=mvappend(ucast(map_get(input_event, "dest_user_id"), "string", null), ucast(map_get(input_event, "dest_device_id"), "string", null)), body=create_map(["event_id", event_id, "cmd_line", cmd_line, "process_name", process_name, "parent_process_name", parent_process_name, "process_path", process_path]) | into write_ssa_detected_events();
The SPL above uses the following Macros:
windows_system_binary_proxy_execution_msiexec_remote_download_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 process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
Known False Positives
False positives may be present, filter by destination or parent process as needed.
Associated Analytic Story
|35.0||70||50||An instance of spawning $process_name$ was identified on endpoint $dest_device_id$ by user $dest_user_id$ attempting to download a file.|
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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