Windows Update Can Hurt Security 220
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."
Quiz (Score:5, Funny)
Windows _____________ Can Hurt Security
Re:Quiz (Score:5, Funny)
Fill in the blank:
Windows _____________ Can Hurt Security
Re:Quiz (Score:4, Insightful)
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Windows' crap security affects everyone.
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I think FTA is wrong: "a fundamental tenant of security is to conservatively estimate the capabilities of attackers". That means that you should always underestimate the capabilities of attackers. WTF?
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$comment =~ s/FTA/TFA/ ;
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Doesn't matter (Score:5, Insightful)
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.
Re:Doesn't matter (Score:5, Insightful)
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Well, either that, or you're advocating not issuing patches at all. That sounds like a pretty bad idea.
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Also has the advantage of the first security update moving everything to the latest version instead of needing 30 patches to get there.
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Re:Doesn't matter (Score:4, Insightful)
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One real world example of essentially the same thing: FIRST Robotics [usfirst.org] wants to make sure that everyone has access to the game manual at the same time at the start of the build season without creating a massive load on their servers, and to make it available for those who don't have internet access where they watch the kickoff. They begin distributing an encrypted version of the manual a week in advance, then release the decryption key
Which just shifts the problem. (Score:5, Interesting)
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.
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Sounds insane at the first glance, could make more sense with a bit of tweaking. There is a very large number of machines wanting the fix. Now, one may safely assume that the majority of machines get a "good" fix, and only a few machines try to seed a backdoor. If you find a way to connect to your peers and ask them for some footprint of their patch (MD5, CRC, whatever), you can validate whether the fix you ge
No hash can be guaranteed secure forever (Score:4, Interesting)
And CRC was never designed to be in the least secure against that sort of thing in the first place. It's a good error checker, but it's not secure.
Yes, there are newer hashes that don't currently have any known vulnerability. But none of which you can be confident that they'll still have no vulnerability in half a decade's time. And if Microsoft were to build what you're suggesting into Windows, a vulnerability beign discovered in whatever hash they used would be a death-knell. How could Microsoft possibly fix it? Distribute a patch to change the hash -- over the compromised patch distribution network?
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Meanwhile asynchronously installing patches throughout your enterprise willy nilly the moment they show up will eventually bring your mission critical systems down.
Increasing security at the expense of stabilit
Re:Doesn't matter (Score:5, Insightful)
Steam has no problem distributing games to players so that they can all unlock them on release day. All you have to do is preload the patch with staggered downloads but not send out the key until the same time. Then all machines can decrypt and patch and install them at roughly the same time, helping to greatly cut down on the time between when the patch can be figured out and the time that machines are still vulnerable.
Not fool-proof, of course, but it seems like something Microsoft should seriously consider doing.
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The current system works fine for those people who autopatch. It takes only a very short time to get the latest patch, shorter than it takes to get the bug, find a good page to work it onto, build up enough trust to get people there, and then deploy it. All this really affects is those users who don't patch their machines.
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Nonetheless, outside of these two cases, it seems like Microsoft is being targeting because, well, they're Microsoft. They have a huge market share and a really good update management system, so they're a big target for something like this. That coupled with their history of vulnerabilities, and it's
Nope. That's a logic error. (Score:2)
Nope. If that were correct, then Apple would see 5% (or so) of the "virus" development out there.
There are millions of Macs out there. If cracking them w
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It's easy to understand why the researchers picked Microsoft's Windows Update over Apple's Software Update. We're not talking about exploits, we're talking about the paper.
Well you were not very clear. (Score:2)
I do not see them picking Windows because it is Windows.
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Re:Nope. That's a logic error. (Score:5, Insightful)
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.
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And you can't hide what the patch fixes.
Actually, I disagree. What if Microsoft obfuscated or encrypted executables the same way that (I've heard) Apple does? Then, any vulnerable executable could be fixed and re-encrypted, and the diff between the two versions would just look like garbage. To get the real data, one would need to break the (obfuscation-based) encryption, but that would take a few weeks (plenty of time for everyone that cares to patch themselves). This depends on Microsoft changing the encryption scheme frequently, like Apple doe
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The only way you can stop this is if all system data was encrypted and the user was not trusted with the keys to decrypt.
Now where have I heard that before??? Hmmm
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There are plenty of ways to do encryption, ultimately you'd need some form of DRM to make it work. Because at some point, it'd need to be decrypted into memory on the client's machine, and without DRM, there is nothing to stop a 3rd party app from retrieving it from memory.
Obfuscation however could work pretty well, because if they patched not just the exploit, but shuffled everything around in the process, they could
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If the executable and libraries all run in memory encrypted or unencrypted wouldn't you be able to tell what the patch changed by comparing an unpatched versus patched process in memory? It would obviously be more difficult because the executable would actually have to be used in a method that the patch affected.
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Re:Doesn't matter (Score:5, Insightful)
1) Turned on
AND
2) Connected to the internet
at the ANY one time. It doesn't matter if it's 1 packet or 150 packets if the computer is off or not currently connected.
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The day my ISP starts controlling wether my machine is "up to date" enough to use it is the day I get a new ISP.
Plus, it would be over-estimating end-users to think they'd get some fancy router because it lets them wait a bit longer before using their computers....
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However, would such a scheme be compatible with free software? Under the GPL, would a Linux distributor be permitted to send out encrypted binary patches and only reveal the decryption key later?
Why not? The distribution isn't complete until the key is published. I don't think a ciphertext would count as a creative work on its own. It certainly doesn't violate the spirit of the GPL.
Of course, there might be issues with distributing only binaries (encrypted or not) without complete corresponding source code (or the requisite written offer), but that's a different question.
If you distributed binaries in cleartext, but encrypted the corresponding source code, then you might have a problem.
Liability problem? (Score:2, Insightful)
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Which just shifts the problem. (Score:4, Insightful)
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 (or simultaneously) 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 patche 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.
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The bad guys can't crack a symmetric cipher like AES (or if they can, we are all in much worse trouble than we thought). Similarly they can't break in to servers belonging to Microsoft to grab the key early (or if they can, Microsoft and its users are all in much worse trouble than we thought).
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How would one determine that "all" clients had finished downloading the encrypted patch?
Couldn't I prevent the patch from ever being applied anywhere in the world by spoofing a client which keeps reporting "haven't finished downloading it yet..." back to the central authority forever?
Re:Doesn't matter (Score:5, Insightful)
I don't know if that's the whole reason, but I bet that it's part of it.
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Re:Doesn't matter (Score:5, Insightful)
are you 100% sure you're not still running some vulnerable code?
If I've restarted the server process, yes.
What if bash had a vulnerability, and you installed the new version but old bash processes were still running?
I'd kill all bash processes.
if you're really lucky then the package manager will know to restart the service after installing a new version.
That's been quite standard for a long time. I know Redhat includes that in their RHEL distribution. So I wouldn't exactly call that "really lucky"
But how confident are you that everything is covered?
Unless it's something critical like a shared library vulnerability, very confident. In the case of a shared lib, it might be easier to just reboot the machine than restarting all the various processes. But at least you have a choice in the matter, which 9/10 of the time you simply don't with Windows.
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Right, and you religiously do this every time after the automated update runs? And so do all other Linux users?
[auto-restarting a service after installing an update]
For server programs like Apache, maybe. It depends on the rpm spec file. But certainly not for bash, or perl, or X11, or many other things that might have a security bug. As I said, it's mostly a question of luck.
I'm not saying that forcing a reboot is always better - cer
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You can never distribute patches synchronously to all the PC:s in the world.
Maybe you could.
Consider that a patch is first distributed as an encrypted file. The decryption key is kept secret until everyone has a chance to download the patch. At a pre-determined time, the decryption key is transmitted to everyone (the key is quite small so everyone getting it at nearly the same time shouldn't overwhelm the distribution server; a simplistic multicast or tree-like distribution system (like NTP) could further alleviate this problem). So then every computer patches itself at more-or
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Easy with OSS, I have no idea how MS is supposed to do it, though.
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The proper solution is to minimise attack surface. Run minimal services that expose minimal resources.
Furthermore, onion analogies only work in cartoons. The problem with "layered security" is that it implies that more layers is always better. Honeypots, complex email scanners, and IDS can be helpful in the right sit
No prob... (Score:2, Funny)
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It'd take a lot longer, and be only slightly harder, if all of the binaries were encrypted. They've still got to run, though, so the images have to be available in memory.
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Worst possible way to critize Windows Updates (Score:5, Insightful)
That's the biggest problem. (Score:2)
The vendor MUST ship with the minimum number of services running BY DEFAULT and with the minimum rights for those services.
My problem with Microsoft on that is that they did NOT minimize the number of services. They put a software firewall in front of them.
Meanwhile, I can put a vanilla Ubunut workstation on the 'Web without a firewall.
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In other words, try to enforce something in a country that doesn't care about your problems, since it has its own.
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And then what about updates that need a reboot? Should that be automatic and instant?
This is a very hard problem, with no easy answer aside from "build it with security from the ground up"
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Most users turn on auto-update; instant doesn't add any downsides. If you're worried about that, then you need to do your job as a sysadmin, and this wouldn't change anything there either (since you'd have auto-update turned off in either case). Things requiring a reboot would be handled however they are currently -- just with less latency between the patch being available and everyone having it.
You're right, of course, that there is no easy answer.
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Re:Worst possible way to critize Windows Updates (Score:5, Insightful)
From the summary: "Such as Windows Update... can detract from overall security, and should be redesigned."
The ellipse represents 14 pages of information in this sentence. And the Actual PDF doesn't say it detracts from security, but rather that the scheme is insecure. Which is quite a difference. Normally I don't do this, but the quote is really stupid when put the way the contributor or editor put in there. The article was interesting enough on its own accord (automatic patch-exploit generation) without having to throw your own personal cracks in there.
Let's grow up, people.
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update this, fuckers (Score:5, Insightful)
And you are.
Sorry.
Re:update this, fuckers (Score:5, Insightful)
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I don't mind being a 70k a year janitor. Dunno if it would be cheaper to just not make a mess, but hey, I certainly won't complain about it. Every time your computer barfs, my cash register jingles.
Which only works for small messes (Score:4, Insightful)
That works for small messes.
It doesn't work for somebody getting hold of the company's trade secrets, client list, bidding information, road map, and headhuntable employee names and pay scale.
It doesn't work for somebody cracking the information on the company accounts and transferring the cash reserves to themselves via untraceable paths.
It doesn't work for somebody destroying or corrupting the IT infrastructure - especially the databases - and taking the company out of business for days or forever, causing key employees to quit or be fired, etc.
It doesn't work for somebody corrupting industrial process control infrastructure and literally destroy plants and kill employees, or cause the company to build and ship defective products.
I could go on.
Cleaning up IT graffiti is one thing. Cleaning up IT nuclear strikes is quite another.
IMHO any corporate IT exec who treats malware like graffiti, rather than an early warning of something more serious, is negligent in his fiduciary duty to the shareholders and perhaps criminally negligent in his duty to protect the lives and health of the employees. (Pity that most of 'em do treat the threat in this way. B-( )
Windows bashing aside ... (Score:5, Insightful)
... 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.
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It's called "IP Multicast" (Score:2)
It's called "IP Multicast".
Does YOUR ISP support it?
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However, the fact that you can obtain the code makes no difference, and may even be a hinderance, since an exploit can be created here in as little as a minute just from the binaries.
The major difference here between Windows and Linux is that Windows is a lot more of a mono-culture. In the linux world, there is no guarantee that an exploit will be availabl
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How can it be hinderance to have sources where problem exists and where it is fixed? Just run a damn diff of them and there you have it.
Where's the WellDuh Tag (Score:2)
I've heard reports of bugs created by patches and patches to fix bugs from patches that only took it back to base version.
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Not only can you reverse engineer the binary, but you have access to the source code and it's modifications. If you read bug trackers or dev mailing lists, you can even pick up security vulnerabilities before the patch is even released just by looking at bugs and diff files.
You can't put the toothpaste back in the tube, people. Arguing that that means you shouldn't brush your teeth is ridiculous.
M$ need to stop haveing a fixed update day and go (Score:2)
Instant patching is never going to happen. (Score:4, Informative)
The fundamental problem here is that a lot of security depends on single points of failure. A real security system relies on the "defense in depth" approach.
How is this limited to Windows? (Score:5, Insightful)
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.
From the PDF: (Score:5, Informative)
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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Why not use the bot nets for this kind of stuff? I mean, previous article today already showed, that they have a quite effective way of patching arbitrary systems and distribute mass content.
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security through obscurity - don't provide patches at all, and never release the source code. This will make it much harder for script kiddies.
It should be noted that Microsoft Research is aligned with the CMU Computer Science department - vis a vis the Microsoft Carnegie Mellon Center for Computational Thinking. That is either ironic, or obvious depending on your viewpoint (either it can fuel Microsoft to do a more thorough job of releasing early, often and being more transparen
2 and 3 are also vulnerable to countermeasures (Score:2)
This can make things worse:
The distribution of the patch alerts the bad guys to the existence of the bug.
- They can use their botnet infrastructure to get the key early and DDoS the key servers (possibly simultaneously, using the botnet to grab the key thr
No fix feasible (Score:5, Interesting)
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.
So what would the new system look like? (Score:2)
This article is dumb. (Score:4, Interesting)
Essentially, these people wrote a paper which says that hackers can analyze Windows Updates and figure out how to attack systems that aren't patched yet thereby. It goes into theory and proofs of that. Thanks, everyone else knew this about Windows Update years ago, probably for about as long as there's been a Windows Update.
It then proposes some solutions which are all, on the whole, worse than the status quo for various reasons. For example, forcing all Windows machines, whether they're turned on or connected to the internet or not, to patch at the very same instant is not realistic.
They should've called this thing: "Windows Update has problems. Magic can fix them."
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If you had, you'd know that this paper did not say that "hackers can analyze Windows Updates and figure out how to attack systems that aren't patched yet thereby". What it did say was that it is possible to write software that can analyze the update for you and churn out an exploit for the security issue identified thereby...in a matter of seconds.
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Regardless, none of their proposed solutions are viable.
Automatically deriving exploits by theorem proving (Score:5, Informative)
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.
It's impressive (Score:4, Interesting)
For instance, when they come up with the exploit for WMF reader vulnerability, they're not making you a new WMF file (as I understand, anyway).
One thing that interested me is the model they invented. The binary differencing was off-the-shelf stuff from eEye. But their model of the x86 machine (cpu, instruction side effects, registers, and memory) is new, and that seems like something that could have been written previously.. I'm surprised they needed to do this. They also define a space of functions that examine the model to determine if badness has happened, for each specific kindof badness they're interested in, i.e. return address changes during execution of call.
They also appear to require execution traces of P (or P') to run under a machine monitor; I don't think from the instructions in P they work backwards from P/P' difference lines and construct initial conditions of the machine state. Even if that _is_ what they were doing, they only model the salient portions of the binary, not the outside system.
Even so, what they're doing here is fantastic. The things they're not doing (automatically creating files that trigger the exploit) are all possible offshoots from this paper, if one were to have sufficient computing power and time to create models of the salient portions of the system. For each different data flow into the instruction/memory space, the model would need to describe the line of demarcation. In the case of the WMF/PNG vulnerabilities, that line is on the other side of readfile or mmap or whatever. (i.e. the bytes that trigger the exploit come from the disk). Building a file on disk in a certain way to cause a sequence of x86 instructions to produce the desired memory is a hard problem in and of itself, although I perhaps possible with the tools and techniques they've already got.
The same would be true of the ASP.NET vulnerability. I beleive they can work backwards from exploit to the in-memory representation of a URL request. At that point, knowing that URLs come from the outside hostile internet, through IIS, etc etc etc, is vuln-specific domain expertise. However, a library of injection points (file on dist, URL request from network, packet from network, etc) could be built around the analysis model. The analysis engine works backwards until it says "here is the memory precondition that leads to an exploit, now i rely on an injection plugin to acheive that memory state."
Ok, it's bad. Got any better ideas? (Score:5, Insightful)
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.
2 points (Score:3, Insightful)
2) I think we are forgetting that the exploits still need to be distributed, and the article refers to worms, but how is this different from any other worm/virus?
Smarter viruses will attack weaknesses that are yet widely known or patched, so those that use exploits based on public patches are 1) stupider and 2) more predictable.
So this is less of an "update how" problem, and rather more of an antivirus problem. The previous might be impossible to solve, but the latter we have solutions for.
MS is one step ahead (Score:2)
By making a users computer useless, the goal is to get fewer people using computers, thereby reducing security problems.
What's important about this: (Score:4, Insightful)
This negates the claim that hiding the source code increases security.
In other news... (Score:2)
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The point is that on my own machine, I can examine the patch and the old file, and then generate an exploit. If the vulnerability was in a running service (say, the firewall code or the Server service), then I can create a worm which will propagate through the network.
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Something like this [gawker.com], I would imagine... ^_^