Am 12.04.2013 13:44, schrieb Josh Bressers:
On Thu, Apr 11, 2013 at 12:54 PM, Reindl Harald
<h.reindl(a)thelounge.net> wrote:
>
> which is exactly the goal ASLR is desigend for
>
It's designed to make certain types of attacks more difficult. It
doesn't make them impossible, just much harder.
Here is an example.
When you write a security exploit, you generally have to do things
like call into system libraries to do useful things. Generally you
have a limited amount of room for your exploit's "payload", so the
idea is to just leverage what the system can already do. Calling
system() would be an example of this. Now long ago, before things like
ASLR, if you had access to the binary you wanted to attack, you could
inspect the binary to see what the address of system() was. It didn't
change between runs of the binary, so I could hard code that address
into my exploit. With ASLR, every time you run the binary the address
of various system calls is now basically random (it's not exactly, but
that's an exercise for the reader to figure out). If your payload
needs to call system(), you need a way to figure out what that address
is before you can use it, the added step should make it more difficult
to exploit a problem. The technology isn't fool proof of course, but
that's a topic for another day.
that is nothing new
that is the reason why any application which get input data
from the internet has to use ASLR and anything which makes
ASLR less effective has to be considered a bug
yes there is performance AND security
but in these days security first
there are so many pieces of software written these days with
no care about performance and mostly security is not the reason
for most developers wasting ressources that there is no excuse
fix the really performance bugs in code but not compensate the
overall situation with prelink and lesser security at all