splunk-security_content/docs/_posts/2021-09-16-detect_mshta_renamed.md

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title	excerpt	categories	last_modified_at	toc	toc_label	tags
Detect mshta renamed	Signed Binary Proxy Execution, Mshta	Endpoint	2021-09-16	true		Signed Binary Proxy Execution Defense Evasion Mshta Defense Evasion Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

The following analytic identifies renamed instances of mshta.exe executing. Mshta.exe is natively found in C:\Windows\system32 and C:\Windows\syswow64. This analytic utilizes the internal name of the PE to identify if is the legitimate mshta binary. Further analysis should be performed to review the executed content and validation it is the real mshta.

• Type: Hunting
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-09-16
• Author: Michael Haag, Splunk
• ID: 8f45fcf0-5b68-11eb-ae93-0242ac130002

ATT&CK

ID	Technique	Tactic
T1218	Signed Binary Proxy Execution	Defense Evasion

| T1218.005 | Mshta | Defense Evasion |

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_mshta` by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.original_file_name 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `detect_mshta_renamed_filter`

Associated Analytic Story

• Suspicious MSHTA Activity

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.

Required field

• _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

Kill Chain Phase

• Exploitation

Known False Positives

Although unlikely, some legitimate applications may use a moved copy of mshta.exe, but never renamed, triggering a false positive.

RBA

Risk Score	Impact	Confidence	Message
80.0	80	100	The following process_name has been identified as renamed, spawning from parent_process_name.

Reference

• https://github.com/redcanaryco/AtomicTestHarnesses
• https://redcanary.com/blog/introducing-atomictestharnesses/

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/T1218.005/atomic_red_team/windows-sysmon.log

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