Modification Of Wallpaper

Try in Splunk Security Cloud

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

• Last Updated: 2021-06-02
• Author: Teoderick Contreras, Splunk
• ID: accb0712-c381-11eb-8e5b-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1491	Defacement	Impact

Kill Chain Phase

• Actions On Objectives

NIST

• DE.CM

CIS20

• CIS 10

CVE

Search

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

Macros

The SPL above uses the following Macros:

• security_content_ctime
• sysmon

modification_of_wallpaper_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
• EventCode
• Image
• TargetObject
• Details
• dest
• process_guid
• process_id
• user_id

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.

Known False Positives

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

Associated Analytic Story

• Ransomware
• Revil Ransomware
• BlackMatter Ransomware
• Windows Registry Abuse
• Brute Ratel C4
• LockBit Ransomware
• Rhysida Ransomware

RBA

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

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://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/
• https://news.sophos.com/en-us/2020/04/24/lockbit-ransomware-borrows-tricks-to-keep-up-with-revil-and-maze/

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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