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Hacker Bypasses Windows 7/8 Address Space Layout Randomization
hypnosec writes "Microsoft upped its security ante with Address Space Layout Randomization (ASLR) in Windows 7 and Windows 8, but it seems this mechanism to prevent hackers from jumping to a known memory location can be bypassed. A hacker has released a brilliant, yet simple trick to circumvent this protection. KingCope, a hacker who released several exploits targeting MySQL in December, has detailed a mechanism through which the ASLR of Windows 7, Windows 8 and probably other operating systems can be bypassed to load a DLL file with malicious instructions to a known address space."
Click on link in article...
I'm sure they're aware of that, as is anyone with a shred of knowledge about computer security (or hell, security in general). What is your point?
"16MB (fuck off, MiB fascists)" - The Mighty Buzzard
Fill memory until only enough space is left for loading whatever it is you're trying to load. Obviously the location is predictable since there's only one spot for it.
Is it possible to "rewrite the instruction pointer of the processor to a known heap address
where the shellcode resides quite deterministic" on, say, Firefox on Gnu/Linux [given that flash and java are disabled in the browser]?
This is an ASLR bypass technique, not an actual exploitable vulnerability by itself. The attacker still needs an exploitable memory corruotion vulnerability to start the attack. ASLR+DEP is designed to make it much harder for an attack to gain foothold in the face of such an attack.
An exploitable memory corruption bug could for instance be a buffer overflow or use-after-free bug in a jpeg or gif library. Such a bug allows a small window of opportunity for an attacker. However, with DEP he will have a hard time injecting actual executable code into the attacked process. Instead he will use a programming technique termed ROP (return oriented programming) where he will trampoline to code carefully chosen code fragments residing at known locations.
Think of a buffer overflow bug which allows the attacker to overwrite the return address of the vulnerable function. Instead of returning to the point where thebfunction was called, the instruction pointer will return to whatever the stack was overwritten with through the buffer overflow. The attacker *still* has not gained full control. But if he can overwrite with an address pointing to a piece of code which does all or part of what he needs he can use that. If it only does part of what he needs but ends with a RET, he can make sure that the stack above the original return address points to the Next piece of usable code.
This technique will Work in any process and on any operating system where the attacker is allowed relatively free access to allocate memory. Think browsers where JavaScript can be used to allocate/squeeze memory.
So yes, this is in no way Windows specific. It is interesting because at this point the Windows ASLR is pretty much state of the art. Only recently has OS X achieved randomization of the "dyld" - the OS libraries. Even a single library being loaded in a predictable location may be enough for the agtacker to squeeze through. Linux ASLR is weaker (not as random) and many Linux libraries are still loaded at perfectly predictable locations.
Reading slashdot one-liner: (irm http://rss.slashdot.org/Slashdot/slashdot).rdf.item | fl title,desc*
Every new security feature they can dream up can and will be bypassed with enough time.All they can do is build it hard enough that it takes more time to crack
I'm sure they're aware of that, as is anyone with a shred of knowledge about computer security (or hell, security in general). What is your point?
Legend has it that Finnish field marshal Mannerheim was interviewed by a journalist after the Winter war. The journalist asked him if he had at any time doubted that the Finns would eventually be defeated by the Soviets. Apparently the old man sent the journalist a sharp look and then replied that just because the odds are against you it does not mean you have to make life easy for your attacker. Dunno fi that is true but if I was in computer security, that's what my outlook would be... come up with nasty defences, whey they are breached you ambush the bastards and then come up with a new line of even nastier defences.
Japanese on Iwo Jima was "desperate defense with no hope of victory".
Finnish was "pre-planned defense in order to make enemy bleed so hard, that even Stalin would decide that gains aren't worth the cost".
It succeeded twice with quite possibly the single most insane-looking numbers in history. It was crazy enough to warrant wikipedia page screenshot becoming an internet meme:
http://www.google.com/imgres?imgurl=http://data.whicdn.com/images/18990146/finland-be-afraid-be-very-afraid_thumb.jpg&imgrefurl=http://weheartit.com/tag/soviet%2520russia&h=200&w=240&sz=11&tbnid=e8G9SZNgTBMY-M:&tbnh=87&tbnw=104&zoom=1&usg=__Tk2w1zc2NxuOzEu4OclPzzBZzVc=&sa=X&ei=RjoDUfekBYbKtAaMuYCwCQ&ved=0CCEQ9QEwAw
This success was repeated in 1944 where Finns faced the single biggest offensive in the entire WW2 war European theatre. Soviets focused 20 artillery pieces per every kilometer of the front line. They could literally dig people out of trenches with this much artillery. In the end, finns held out and even pushed back in spite of being completely outnumbered and outgunned. Stalin remembered the lesson from Winter War and signed a peace treaty with Finland allowing it to stay independent again. It ended up going in history as the only country mentioned in Molotov-Ribbentrop that didn't get conquered by either Germany or USSR.
The main difference between these strategies is that Japanese viewed their empire as something holy and to be defended to the death, to the point where survivors should commit suicide if they failed. Finns viewed their country as something of theirs, and to be defended for as long as it remains defensible with as little losses as possible. Key difference was that finnish commanders valued lives of their soldiers very highly for the times. Japanese commanders treated their soldiers as completely disposable pawns. Difference could be explained by the fact that Japan is one of the most populated regions on the planet, while Finland is one of the least populated ones.
It's the advantage of not being a huge country with long and proud history. You learn that to stand between the giants and survive, you need to show humility to the giants in most things, but also show that when needed, you can sting them so painfully, that any potential attempts of capture will not be worth it. And most of all you learn that when you're losing, minimize your losses so you can fight another day.
You're right that it boils down to just looking up the address, but see, this is a chicken-and-egg problem. You're wanting to determine addresses so you can run code, but you must run code in order to look up addresses!
You might as well say that it is easy to get a dinosaur and a dinosaur egg. To get the dinosaur, just wait for a dinosaur egg to hatch. To get the dinosaur egg, just wait for a dinosaur to lay one. Problem solved, right???