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Description

The following detection identifies Microsoft Winword.exe spawning Windows Script Host - cscript.exe or wscript.exe. Typically, this is not common behavior and not default with Winword.exe. Winword.exe will generally be found in the following path C:\Program Files\Microsoft Office\root\Office16 (version will vary). cscript.exe or wscript.exe default location is c:\windows\system32\ or c:windows\syswow64`. cscript.exe or wscript.exe spawning from Winword.exe is common for a spearphishing attachment and is actively used. Albeit, the command-line executed will most likely be obfuscated and captured via another detection. During triage, review parallel processes and identify any files that may have been written. Review the reputation of the remote destination and block accordingly.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-04-12
  • Author: Michael Haag, Splunk
  • ID: 637e1b5c-9be1-11eb-9c32-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566 Phishing Initial Access
T1566.001 Spearphishing Attachment Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name="winword.exe" Processes.process_name IN ("cscript.exe", "wscript.exe") by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `winword_spawning_windows_script_host_filter`

Macros

The SPL above uses the following Macros:

:information_source: winword_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
  • process_name
  • process_id
  • parent_process_name
  • dest
  • user
  • parent_process_id

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

There will be limited false positives and it will be different for every environment. Tune by child process or command-line as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
70.0 70 100 User $user$ on $dest$ spawned Windows Script Host from Winword.exe

: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

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