The following analytic identifies a recently disclosed arbitraty command execution using Windows msdt.exe - a Diagnostics Troubleshooting Wizard. The sample identified will use the ms-msdt:/ protocol handler to load msdt.exe to retrieve a remote payload. During triage, review file modifications for html. Identify parallel process execution that may be related, including an Office Product.
- Type: TTP
Product: Splunk Behavioral Analytics
- Last Updated: 2022-09-15
- Author: Michael Haag, Splunk
- ID: f253f9c2-10f0-4cc8-b469-f505ba8c2038
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 $main = from source | eval timestamp = time | eval metadata_uid = metadata.uid | eval process_pid = process.pid | eval process_file = process.file | eval process_file_path = process_file.path | eval process_file_name = lower(process_file.name) | eval process_cmd_line = process.cmd_line | eval actor_user = actor.user | eval actor_user_name = actor_user.name | eval actor_process = actor.process | eval actor_process_pid = actor_process.pid | eval actor_process_file = actor_process.file | eval actor_process_file_path = actor_process_file.path | eval actor_process_file_name = actor_process_file.name | eval device_hostname = device.hostname | where ((process_cmd_line LIKE "%ms-msdt:/id%" OR process_cmd_line LIKE "%ms-msdt:-id%" OR process_cmd_line LIKE "%ms-msdt:/id%" OR process_cmd_line LIKE "%ms-msdt:%" OR process_cmd_line LIKE "%msdt%") AND process_file_name="msdt.exe") AND (match(process_cmd_line, /(?i).xml/)=true OR match(process_cmd_line, /(?i)it_rebrowseforfile=/)=true OR match(process_cmd_line, /(?i)it_browseforfile=/)=true) AND match(process_cmd_line, /(?i)pcwdiagnostic/)=true --finding_report--
The SPL above uses the following Macros:
windows_execute_arbitrary_commands_with_msdt_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
Known False Positives
False positives may be present, filter as needed. Added .xml to potentially capture any answer file usage. Remove as needed.
Associated Analytic Story
|100.0||100||100||$process_name$ on $dest_device_id$ under user $dest_user_id$ possibly indicative of indirect command execution.|
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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