Office Product Spawning Windows Script Host

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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 Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2023-02-15
• Author: Michael Haag, Splunk
• ID: b3628a5b-8d02-42fa-a891-eebf2351cbe1

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1566	Phishing	Initial Access

T1566.001

Spearphishing Attachment

Initial Access

Kill Chain Phase

• Exploitation

NIST

CIS20

CVE

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name IN ("winword.exe","excel.exe","powerpnt.exe","mspub.exe","visio.exe","onenote.exe","onenotem.exe","onenoteviewer.exe","onenoteim.exe", "msaccess.exe") Processes.process_name IN ("wscript.exe", "cscript.exe") by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)` 
| `office_product_spawning_windows_script_host_filter`

Macros

The SPL above uses the following Macros:

• security_content_summariesonly
• security_content_ctime

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.

Supported Add-on (TA)

List of Splunk Add-on’s tested to work with the analytic.

• Splunk Add-on for Sysmon

Required fields

List of fields required to use this analytic.

• _time
• Processes.dest
• Processes.user
• Processes.parent_process_name
• Processes.parent_process
• Processes.original_file_name
• Processes.process_name
• Processes.process
• Processes.process_id
• Processes.parent_process_path
• Processes.process_path
• Processes.parent_process_id

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

Known False Positives

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

Associated Analytic Story

• Spearphishing Attachments
• Remcos

RBA

Risk Score	Impact	Confidence	Message
63.0	70	90	office parent process $parent_process_name$ will execute a suspicious child process $process_name$ on host $dest$.

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://blog.cluster25.duskrise.com/2022/09/23/in-the-footsteps-of-the-fancy-bear-powerpoint-graphite/
• https://www.fortinet.com/blog/threat-research/latest-remcos-rat-phishing
• https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/trojanized-onenote-document-leads-to-formbook-malware/

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

• https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566.002/atomic_red_team/windows-sysmon.log

source | version: 3