Windows System Binary Proxy Execution MSIExec Unregister DLL
Description
The following analytic identifies the usage of msiexec.exe using the /z switch parameter, which grants the ability for msiexec to unload DLLRegisterServer. Upon triage, review parent process and capture any artifacts for further review.
- Type: TTP
- Product: Splunk Behavioral Analytics
- Datamodel: Endpoint_Processes
- Last Updated: 2022-08-31
- Author: Michael Haag, Splunk
- ID: df76a8d1-92e1-4ec9-b8f7-695b5838703e
Annotations
Kill Chain Phase
- Exploitation
NIST
CIS20
CVE
Search
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, "%/z %") OR like (cmd_line, "%-z %"))
| 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();
Macros
The SPL above uses the following Macros:
windows_system_binary_proxy_execution_msiexec_unregister_dll_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- dest_device_id
- process_name
- parent_process_name
- process_path
- dest_user_id
- process
- cmd_line
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
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
35.0 | 70 | 50 | An instance of spawning $process_name$ was identified on endpoint $dest_device_id$ by user $dest_user_id$ attempting to unregister a DLL. |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
- https://thedfirreport.com/2022/06/06/will-the-real-msiexec-please-stand-up-exploit-leads-to-data-exfiltration/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218.007/T1218.007.md
Test Dataset
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
source | version: 1