Defeating XP SP2 Heap Protection

hobo2k writes "XP SP2 included canary values and hardware-implemented execution protection in order to avoid exploitable buffer overruns. Now Positive Technologies has released an article describing one way that protection could be bypassed. To solve the problem, they provide a program which disables the small allocation heap as described here. CNET reports that SP2 has been foiled."

Comments

Re:i know the drill

[freeJustin]

mayve you didnt read correctly this is a core issue, so to rephrase "I know the drill, *nix"

Re:In hardware?

[Anonymous Coward]

How many of these rely on the hardware to protect them?

Ummm... all of them?

Memory protection requires hardware support to work, and every version of UNIX, Linux, NT (right from the beginning) and Win9x all use hardware support to implement memory protection.

It seems that you have hardware memory protection mixed up with the NX (no execute) bit. All that the NX bit does is nothing more than mark memory allocated on the heap as non executable. The application is completely free to allocate executable memory, just that a normal malloc() does not cut it for this purpose.

This is a very good feature. The reason is that 99.99% of apps never need to execute code created on the heap. The only exceptions are things that JIT code like the Java VM.

Many buffer overruns that result in exploits rely on heap memory being executable. By requiring a very small set of programs to be fixed, you can eliminate a whole type of security flaw. Is it the be all and end all? No its not. But it sure helps.

Re:Linux/NX/AMD64

[DaHat]

Last I checked it already was.

http://news.zdnet.com/2100-3513_22-5227102.html/
http://linuxgazette.net/107/pramode.html/
http://kerneltrap.org/node/3240?PHPSESSID=262a094f ee677def32a8cc4d1b858f99/
http://searchenterpriselinux.techtarget.com/origin alContent/0,289142,sid39_gci969248,00.html/

Just to name a few

Re:NX bit?

[YU Nicks NE Way]

The article description is a bit deceptive. NX is independent of DEP here. The alleged exploit only works for the small heap on machines without NX, not for machines with NX. NX stops this exploit cold.

Re:An agrarian view on alternatives for XP SP2

[bluefoxlucid]

BSD is under the BSD license. You may rewrite it, steal their code, and not give it out.

You can build things with GCC and not GPL them.

You can build things and link to libraries that are GPL and not GPL them.

So, you can develope apps for linux, using only your own code and any code that BSD people threw under the BSD license, and build them against open source libraries to use those, and have an MS style EULA and closed source.