PointGuard: It's not the Size of the Buffer, it's the Address of the Pointer

[Crispin Cowan <crispin () immunix com>]

This seems topical to today's discussion of buffer overflow defenses:

   "PointGuard: Protecting Pointers From Buffer Overflow
   Vulnerabilities". Crispin Cowan, Steve Beattie, John Johansen and
   Perry Wagle. To appear at the 12^th USENIX Security Symposium
   <http://www.usenix.org/events/sec03/>, Washington DC, August 4-8,
   2003. Paper
   <http://immunix.com/%7Ecrispin/pointguard_usenix_security2003.pdf>
   and Talk
   <http://immunix.com/%7Ecrispin/pointguard_usenix_security2003.ppt>.

   PointGuard^TM : Protecting Pointers From Buffer Overflow Vulnerabilities
   Crispin Cowan, Steve Beattie, John Johansen and Perry Wagle
   Immunix, Inc.

   Despite numerous security technologies crafted to resist buffer
   overflow vulnerabilities, buffer overflows continue to be the
   dominant form of software security vulnerability. This is because
   most buffer overflow defenses provide only partial coverage, and the
   attacks have adapted to exploit problems that are not well-defended,
   such as heap overflows. This paper presents PointGuard, a compiler
   technique to defend against most kinds of buffer overflows by
   encrypting pointers when stored in memory, and decrypting them only
   when loaded into CPU registers. We describe the PointGuard
   implementation, show that PointGuard s overhead is low when
   protecting real security-sensitive applications such as OpenSSL, and
   show that PointGuard is effective in defending against buffer
   overflow vulnerabilities that are not blocked by previous defenses.

Thanks to Snax and the Shmoo for a better tag line: It's not the Size of 
the Buffer, it's the Address of the Pointer

Crispin

--
Crispin Cowan, Ph.D.           http://immunix.com/~crispin/
Chief Scientist, Immunix       http://immunix.com
           http://www.immunix.com/shop/