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Description

The following analytic will identify a Windows Office Product spawning WScript.exe or CScript.exe. Tuning may be required based on legitimate application usage that may spawn scripts from an Office product.

  • Type: TTP
  • Product: Splunk Behavioral Analytics
  • Datamodel: Endpoint_Processes
  • Last Updated: 2023-02-15
  • Author: Michael Haag, Splunk
  • ID: 3ea3851a-8736-41a0-bc09-7e4485b48fa6

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566 Phishing Initial Access
T1566.001 Spearphishing Attachment Initial Access
Kill Chain Phase
  • Exploitation
NIST
  • PR.PT
  • DE.CM
CIS20
  • CIS 8
CVE 


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| 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=lower(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 parent_process_name IS NOT NULL 
| where (like(parent_process_name, "%\\\\winword.exe") OR like(parent_process_name, "%\\\\excel.exe") OR like(parent_process_name, "%\\\\powerpnt.exe") OR like(parent_process_name, "%\\\\mspub.exe") OR like(parent_process_name, "%\\\\visio.exe") OR like(parent_process_name, "%\\\\msaccess.exe")) AND (process_name="wscript.exe" OR process_name="cscript.exe") 
| 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:

:information_source: office_product_spawning_windows_script_host_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

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 based on macro based approved documents in the organization. Filtering may be needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
63.0 70 90 A Microsoft office parent process $parent_process_name$ has spawned a suspicious child process $process_name$ on host $dest$.

:information_source: 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

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: 2