splunk-security_content/docs/_posts/2021-04-12-excel_spawning_windows_script_host.md

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Excel Spawning Windows Script Host	Security Account Manager , OS Credential Dumping	Endpoint	2021-04-12	true		Security Account Manager OS Credential Dumping Credential Access Credential Access Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

The following detection identifies Microsoft Excel spawning Windows Script Host - cscript.exe or wscript.exe. Typically, this is not common behavior and not default with Excel.exe. Excel.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.exeorwscript.exe` spawning from Excel.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: 57fe880a-9be3-11eb-9bf3-acde48001122

Annotations

ATT&CK

ID	Technique	Tactic
T1003.002	Security Account Manager	Credential Access

| T1003 | OS Credential Dumping | Credential Access |

Kill Chain Phase

• Exploitation

NIST

CIS20

CVE

Search

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

Macros

The SPL above uses the following Macros:

• security_content_ctime
• security_content_summariesonly

ℹ️ excel_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 field

• _time
• process_name
• process_id
• parent_process_name
• dest
• user
• 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.

Known False Positives

False positives should be limited, but if any are present, filter as needed. In some instances, cscript.exe is used for legitimate business practices.

Associated Analytic story

• Spearphishing Attachments

RBA

Risk Score	Impact	Confidence	Message
80.0	80	100	An instance of parent_process_name spawning process_name was identified on endpoint dest by user user, indicating potential suspicious macro execution.

ℹ️ 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://app.any.run/tasks/8ecfbc29-03d0-421c-a5bf-3905d29192a2/
• https://attack.mitre.org/techniques/T1566/001/

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/T1566.001/macro/windows-sysmon.log

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