splunk-security_content/docs/_posts/2021-06-02-modification_of_wallpaper.md

title, excerpt, categories, last_modified_at, toc, toc_label, tags

title	excerpt	categories	last_modified_at	toc	toc_label	tags
Modification Of Wallpaper	Defacement	Endpoint	2021-06-02	true		Defacement Impact Splunk Enterprise Splunk Enterprise Security Splunk Cloud Endpoint

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Description

This analytic identifies suspicious modification of registry to deface or change the wallpaper of a compromised machines as part of its payload. This technique was commonly seen in ransomware like REVIL where it create a bitmap file contain a note that the machine was compromised and make it as a wallpaper.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-06-02
• Author: Teoderick Contreras, Splunk
• ID: accb0712-c381-11eb-8e5b-acde48001122

ATT&CK

ID	Technique	Tactic
T1491	Defacement	Impact

Search

`sysmon` EventCode =13  (TargetObject= "*\\Control Panel\\Desktop\\Wallpaper" AND Image != "*\\explorer.exe") OR (TargetObject= "*\\Control Panel\\Desktop\\Wallpaper" AND Details = "*\\temp\\*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Image TargetObject Details  Computer process_guid process_id user_id 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `modification_of_wallpaper_filter`

Associated Analytic Story

• Ransomware
• Revil Ransomware
• BlackMatter Ransomware

How To Implement

To successfully implement this search, you need to be ingesting logs with the Image, TargetObject registry key, registry Details from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Required field

• _time
• EventCode
• Image
• TargetObject
• Details
• Computer
• process_guid
• process_id
• user_id

Kill Chain Phase

• Exploitation

Known False Positives

3rd party tool may used to changed the wallpaper of the machine

RBA

Risk Score	Impact	Confidence	Message
54.0	60	90	Wallpaper modification on dest

Reference

• https://krebsonsecurity.com/2021/05/a-closer-look-at-the-darkside-ransomware-gang/
• https://www.mcafee.com/blogs/other-blogs/mcafee-labs/mcafee-atr-analyzes-sodinokibi-aka-revil-ransomware-as-a-service-what-the-code-tells-us/

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/malware/revil/inf1/windows-sysmon.log

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