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Windows Update Can Hurt Security
An anonymous reader writes "Researchers at Carnegie Mellon University have shown that given a buggy program with an unknown vulnerability, and a patch, it is possible automatically to create an exploit for unpatched systems. They demonstrate this by showing automatic patch-based exploit generation for several Windows vulnerabilities and patches can be achieved within a few minutes of when a patch is first released. From the article: 'One important security implication is that current patch distribution schemes which stagger patch distribution over long time periods, such as Windows Update... can detract from overall security, and should be redesigned.' The full paper is available as PDF, and will appear at the IEEE Security and Privacy Symposium in May."
Windows _____________ Can Hurt Security
You are damned either way. The only way to avoid complete damnation from security vulnerabilities is to run a large number of different operating systems, but then you are damned to live a life in complete confusion about system maintenance instead.
The onion principle is a general security term that has been defined a long time ago, but the fact that we are all online in some way or another all the time means that the onion is rotten.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
There is no good solution to this problem -- that fixing something makes it easier to find old problems. At some point, users need to be responsible enough to apply updates.
"Thanks for all the money you paid to us. We've used it to buy off ISO among other things" -Microsoft
Profitability is key, not security. Think of sysadmins as janitors. We pay you to wipe up the mess. It's not worth our while to invest in systems that don't create a mess as long as janitors are cheap enough to come with their electronic mops and buckets.
And you are.
Sorry.
... patch based security is also the model linux uses (as far as I understand).
Furthermore, for Linux access to the unpatched code is also easy to obtain.
Somebody please correct me if I'm mistaken.
Tie two birds together: although they have four wings, they cannot fly. (The blind man)
Couldn't this process (modified of course) do the same thing to any update for any software at all?
How exactly is this news? I mean, I should update my software when there's a new patch anyway, but now that THIS has been developed I...need to update my software when there's a new patch... Automating it is a pretty neat trick, and it pretty much destroys any argument for security through obscurity, since it means you couldn't patch any hole to maintain the obscurity, but it's not like security through obscurity in the computer software realm has that amazing a track record in any case.
The PDF outlines three methods of alleviating the problem of staggered patch distribution:
1) Patch Obfuscation: basically an attempt to hide exactly what the patch fixes by padding out the patch with a lot of lines of nonsense. While this might prove effective, it would only be effective until an improved algorithm for discerning the true reason for the patch is found, and in the meantime, it would create its own set of problems, particularly if the level of obfuscation required balloons the size of the patch to an unmanageable degree.
2) Patch Encryption: basically distributing the patch in an encrypted format, waiting until it is reasonable to assume that everyone has the patch, and then transmitting a decryption key to decrypt and apply the patch more or less "simultaneously". Problems: this only pushes the problem back one level; meaning the same method of exploitation is just as possible, while this also creates an unacceptable time lag for patches to be applied, which hackers who write exploits the old-fashioned way can exploit to their considerable benefit.
3) Fast Patch Distribution: basically leveraging technologies like P2P to insure that patches are rolled out...well...fast. Problems again include off-line hoists, as well as hosts who have the misfortune of being on ISPs that take a dim view of P2P.
In summary, none of the methods outlined have much of a chance to combat this new threat.
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~ |rip/\/\aster /\/\onkey
Unfortunately, no fix is feasible. The basic problem is twofold:
- If you tell someone how to fix a problem, you tell them what the problem was.
- It's not possible to push updates to all affected systems simultaneously.
That the first is true should be obvious if you think about it for a minute. As for the second, that comes from the fact that the affected systems are owned by different entities with different requirements and different environments. A fix for a problem affects more than just the fixed software, especially when the fix is in the operating system on which other business-critical software runs. Any fix has to be checked for compatibility with that entity's specific environment, this checking can't start until after the entity has gotten the fix, and everybody's going to take a different amount of time to check and get clearance to deploy.The only "fix" would be a mandatory push to all systems at one time, and that won't be accepted by the people who own the systems unless Microsoft or someone else accepts complete 100% liability for all costs associated with any failure. And I just don't see that happening.
This is fascinating. As someone who's worked with automatic theorem proving and proof of correctness techniques, I'd never thought of using them in this way.
What they're doing works like a proof of correctness system in reverse. They difference executables before and after the patch (which in itself is impressive), then, having isolated the patch, analyze it automatically. Security patches usually consist of adding a test which constrains the valid inputs at some point. So they use a symbolic decision procedure, which is part of a theorem prover, to work back through the code and automatically derive a set of inputs that would be caught by the new test.
This is more than just an attack on Windows Update. It's true automated exploit generation.
This is potentially applicable to any security-critical code that changes over time. One could, for example, have something that watched check-ins to the Linux kernel tree and developed new exploits to current stable releases from them.
If you have a patch, you can diff the original and the patched file and find out what got fixed. No secret here.
So how can you close the gap between fixing and exploiting? That's nothing MS could fix. You have to. Patch early, patch often.
If any message is contained here, it's that if there is a patch out and you didn't use it, you're extremely vulnerable. That's pretty much it, nothing really new here.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Or distribute encrypted patches over the course of a day, then when you publish the key everyone can update
Which shifts the problem from distributing the update to distributing the key.
Of course this does have another advantage: Distributing the encrypted update also distributes notification that there WILL be a key, and can tell the users when. Then it becomes a race to get the key and apply the patch before the bad guys can get the key, generate, and deploy an exploit.
And the downside: The bad guys also know the patch is coming, and when. So they can use their existing botnet(s) to grab a key as soon as possible, then DDOS the key distribution mechanism while they generate and deploy the exploit. This makes things WORSE: A much larger fraction of the machines are vulnerable when the exploit deploys.
Still worse: If the bad guys crack the encryption, or manage to break in and grab the key early, they get to automatically generate and deploy an exploit while NOBODY has the fix. Oops!
Ditto even if they don't crack the patch - but the patches exposes that a vulnerability exists and perhaps what module has it, and they find and exploit the vulnerability before the key deploys.
= = = =
In a battle between weapons and armor, weapons eventually win.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
While Apple may be more secure, until you get 50% market share your not going to get 50% of the effort put into attacking you.
IranAir Flight 655 never forget!