Re: Digital Armaments Security Advisory 20.01.2007: Grsecurity Kernel PaX Vulnerability

[hugo () infohacking com]

Hi,

quoting grsec developer: "Using the RBAC system's PaX flag support to enforce system-wide MPROTECT enabling could have 
prevented triggering of the bug, since it requires the creation of an executable stack to trigger the vma mirroring 
bug."

I 've tested the exploit on 2.6 kernel in an Alpha platform with MPROTECT RBAC protection activated -wich is our 
default setting :-)- and it doesn't work...

hugo@alpha ~ $ ./xploit
mprotect map1 base: Permission denied
run chpax -m on this executable

Moreover, even without MPROTECT activated it is important to remenber that OS security must never rely on a single 
layer... a well-configured Grsec system will render very difficult to exploit it -nor at least with a direct vector-. 
On Grsec case, there are some configurations can help prevent/difficult the exploitation: aggressive TPE (Trusted Path 
Execution) configuration + tight RBAC policy + Network Protections will make a pain to exploit this, even locally.

Regards,