0patching a 0-day: Windows gdi32.dll memory disclosure(0patch.blogspot.com)
0patch.blogspot.com
0patching a 0-day: Windows gdi32.dll memory disclosure
https://0patch.blogspot.com/2017/02/0patching-0-day-windows-gdi32dll-memory.html
5 comments
What about getting vendors into changing their patching habbits? Instead of packing some hundred mega patches just provide micro ones when needed? As you said 0day issues are usually (not allways) easy to fix. Probably you alone are skilled enough to check this couple of code instructions by yourself - which is not the case with full-blown patch Tuesday packages. I am pretty sure that process could be much cheaper for MS.
> What about getting vendors into changing their patching habbits? Instead of packing some hundred mega patches just provide micro ones when needed?
This was how things worked previously in the industry. There are a number of disadvantages to companies releasing multiple small patches throughout the month:
1. Users may have to reboot their computers multiple times a week.
2. Large corporations (with their own back-compat worries) do their own extensive validation of patches. Multiple small patches puts a large seriously burden on IT departments.
The industry has moved towards larger update bundles for good reason.
This was how things worked previously in the industry. There are a number of disadvantages to companies releasing multiple small patches throughout the month:
1. Users may have to reboot their computers multiple times a week.
2. Large corporations (with their own back-compat worries) do their own extensive validation of patches. Multiple small patches puts a large seriously burden on IT departments.
The industry has moved towards larger update bundles for good reason.
Another reason, with small patches, especially those that actually do a binary patch instead of replacing affected files, you must apply every single patch that affects that file, and you must apply them in the correct order.
Back in the day when binary patching was the norm, this was a common pain point. Good patches at least did a minimal checksum check to make sure they had the correct starting point. Bad ones made no backups and just went to town, and failures meant reinstalling and trying all over again.
Back in the day when binary patching was the norm, this was a common pain point. Good patches at least did a minimal checksum check to make sure they had the correct starting point. Bad ones made no backups and just went to town, and failures meant reinstalling and trying all over again.
Well, with micropatching you don't need to reboot and you only have to review minimum code changes - and if the patch is not working for you you can unpatch it (with proper permissions, ofcourse).
Pretty sure this specific example would require a reboot, changing a Windows kernel DLL. There seems to be some confusion over whether or not the 0patch tool can update the kernel without a reboot, though. https://news.ycombinator.com/item?id=13775550
Patching a user mode app/dll would not require a reboot, just a restart of the app.
Patching a user mode app/dll would not require a reboot, just a restart of the app.
Hi,
Stanka from 0patch here. If you want to enable or disable (aka "patch" or "unpatch" the application) you don't need do restart the application. Not even if your app is running and you've just install 0patch agent. This is how it is designed to work in user space. When the official MS patch is installed (hopefully with the fix) this particular 0patch won't apply anymore.
As we try to make 0patch agent robust and reliable we don't support kernel mode at this moment - we will make this step slow and with great caution.
As we try to make 0patch agent robust and reliable we don't support kernel mode at this moment - we will make this step slow and with great caution.
Can you please clarify whether or not this specific patch is user mode or kernel mode? @johntb86 mentioned GDI is split and this is the user mode part.
Our micropatch (7 of them, really, for 4 different Windows OS versions) for CVE-2017-0038 is user-mode. As are currently all our micropatches. Processes using gdi32.dll do not need to be relaunched to have it applied.
I believe this code is in gdi32.dll and is one of the few pieces of GDI implemented in user mode. However you'd probably still need to reboot because almost every program in windows is linked with it and would need to be restarted.
the microsoft process cost for many individual patches versus larger collections isn't the real issue. behind the scenes, it should be essentially the same. it is a real issue for customers, particularly in IT, to deal with and manage all of those micropatches. especially in a world where you are responsible for validating every patch against your countless internal apps, deployments of updates are not trivial, and you have scenarios like finance where there is SOX compliance, auditing, etc. this is why the model of patch tuesday and the predictability of knowing when the patches were coming (regardless of number) and ability to plan your testing & deployment was loved by IT departments.
the additional tradeoff you need to consider is that the smaller you make the patches, the larger the number of variations you need to test for later patches, updates, app compat, etc. that is why service packs were a thing - you could baseline after a period of many patches getting out there, and start the process again.
(full disclosure: I used to work on and around some of this at microsoft many moons ago)
the additional tradeoff you need to consider is that the smaller you make the patches, the larger the number of variations you need to test for later patches, updates, app compat, etc. that is why service packs were a thing - you could baseline after a period of many patches getting out there, and start the process again.
(full disclosure: I used to work on and around some of this at microsoft many moons ago)
ryanburk, thanks a lot for your comment. We at 0patch are big fans of MS Patch Tuesday from it's very beginning. It was a huge improvement for appsec for more than decade and it still is. But as active pentesters with more than 15 years of experiences we just noticed that our enterprise customers can not apply patches timely and usually their (also critical) systems remain unpatched for several months. It looks they cannot cope with the amount of update changes and testing so they rather decide not patch. That was even worse than not to have a patch from official vendor.
There is one important technical difference between small pre-PatchTuesday patches and micropatches: pre-PatchTuesday patches were installed binaries (actually complete new version of the product) that are here to stay forever – or at least until patch uninstall or product upgrade. Imagine how hard is patch uninstall on CEO's patch-corrupted system on a business travel, for instance. Micropatches only live in memory, they die with the process. They don’t change file system and installed product, just redirect maliciously used instruction (just instruction, not the whole function) to correct path, if possible. It’s just couple instructions any admin could review by himself and switch of, if there is a problem. I wish I could say that for today’s patching procedures. For us it is the idea worth trying. We just have to simplify updating process for users (and software vendors, too).
p.s.: we are aware Microsoft gave up the idea of hot patching some years ago, but as I know they were not changing just couple of instructions. Please correct me if I’m wrong.
There is one important technical difference between small pre-PatchTuesday patches and micropatches: pre-PatchTuesday patches were installed binaries (actually complete new version of the product) that are here to stay forever – or at least until patch uninstall or product upgrade. Imagine how hard is patch uninstall on CEO's patch-corrupted system on a business travel, for instance. Micropatches only live in memory, they die with the process. They don’t change file system and installed product, just redirect maliciously used instruction (just instruction, not the whole function) to correct path, if possible. It’s just couple instructions any admin could review by himself and switch of, if there is a problem. I wish I could say that for today’s patching procedures. For us it is the idea worth trying. We just have to simplify updating process for users (and software vendors, too).
p.s.: we are aware Microsoft gave up the idea of hot patching some years ago, but as I know they were not changing just couple of instructions. Please correct me if I’m wrong.
It sounds like you should include this brief 'how it works when applied/how this affects your machine' explaination of your tech even in this super-technical deep-dive blog post.
You're absolutely right - we have this information scattered around blog posts and other material but it should be laid out in one place and in not-too-techy language. Thanks for pointing it out.
I assume eventually end users will pay for the fixes they choose to use, and the choice will be based on the level of risk the patch mitigates and the reputation of the entity creating the patch.
I would just choose a different software provider at that point. Though I suppose that could be fairly effective at getting enterprise users who are stubbornly holding on to a particular version of software to move on. Like my IT director for example, who sent a long rambling email to everyone about how horrible it was for all of us that Microsoft was leaving us out to dry by not supporting IE6.
For the record this was in April 2014, after Heartbleed was disclosed. IE6 had a 4% market share at the time, so yeah.
For the record this was in April 2014, after Heartbleed was disclosed. IE6 had a 4% market share at the time, so yeah.
Wow, if I worked for a company that was still on, at latest, Windows XP and Windows Server 2003 in 2014, I think I'd be looking for a different job.
Even my tech-illiterate father, who has a laptop with XP on it, knows enough to not even connect to the internet with it anymore. He mostly uses it to play solitaire currently, and uses a newer laptop w/ Win10 for anything on the internet.
(edit: grammar)
Even my tech-illiterate father, who has a laptop with XP on it, knows enough to not even connect to the internet with it anymore. He mostly uses it to play solitaire currently, and uses a newer laptop w/ Win10 for anything on the internet.
(edit: grammar)
I am looking for a different job, and it's largely in part due to issues with the IT situation. I basically have stuck around this long because while the IT situation is Kafkaesque, I've really liked a lot of other aspects of the job, and it was in a field I feel strongly about.
WMF/EMF has had an infamous history of security problems—most famously, RCE in 2005: https://en.wikipedia.org/wiki/Windows_Metafile_vulnerability
It is truly an awful format.
Surprisingly it is still the only supported vector format in Office...
Surprisingly it is still the only supported vector format in Office...
Hmmm, apparently 2016 and 365 support SVG finally?
https://support.office.com/en-us/article/Insert-SVG-images-i...
Only 17 years after the spec was established.
https://support.office.com/en-us/article/Insert-SVG-images-i...
Only 17 years after the spec was established.
..? I made a bunch of EPS for a coworker's Excel dashboard a while back, worked fine on 2013 and 2007.
Heh, thanks for pointing that out.
Looks like it's a brand new feature only available since this year and only for Office 365 customers (for now, I hope), given that it's not supported on my Office 2016 build.
Looks like it's a brand new feature only available since this year and only for Office 365 customers (for now, I hope), given that it's not supported on my Office 2016 build.
Live patching is gaining the momentum - see Ksplice, Kpatch, kGraft, XEN and similar
This is not live patching.
A 0patch employee stopped by to explain that they live patch user mode only at this point on Windows, kernel mode is a future goal.
https://news.ycombinator.com/item?id=13782830
https://news.ycombinator.com/item?id=13782830
Except with microsoft where they have stopped using their live patching code and just force reboots on the user.
Indeed - hotpatching support was removed in Windows 8. Apparently it was only ever used in a few updates, and some unscrupulous folks took advantage of the capability: https://arstechnica.com/security/2016/04/hacking-group-plati...
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Why does Microsoft not find and instead Google? MS is not a startup and it is their code. Seems weird that Google has to fine their issues.
What does this say about using Google software versus software from Microsoft? Or am I missing something obvious?
What does this say about using Google software versus software from Microsoft? Or am I missing something obvious?
You are expecting Microsoft to test a nearly infinite number of variables to find every flaw. This is not a reasonable position.
However, the question is "if Google can find this, why couldn't Microsoft?" Which is an entirely reasonable question.
Your statement would also make it unreasonable for Google to be able to find this stuff, but we have existence proof that that's not the case.
Your statement would also make it unreasonable for Google to be able to find this stuff, but we have existence proof that that's not the case.
> However, the question is "if Google can find this, why couldn't Microsoft?" Which is an entirely reasonable question.
His position is absurd. Microsoft could have found it. The thing stopping them is the incredible number of tests you would need to perform to find them all.
His position is absurd. Microsoft could have found it. The thing stopping them is the incredible number of tests you would need to perform to find them all.
Why did that stop them, and not Google? I feel like you're refusing to address the main point here - google found this bug. It happened. They told Microsoft about it, and Microsoft hasn't fixed it 100% yet.
No one is denying that google found the bug. No one is denying that microsoft didn't fix it.
The OP asked why Microsoft didn't find this first. The answer is too many things to test. The entire premise of the argument is insane. If microsoft had a viable way to test ALL of the their products for ANY problem, don't you think they would be doing that?
The OP asked why Microsoft didn't find this first. The answer is too many things to test. The entire premise of the argument is insane. If microsoft had a viable way to test ALL of the their products for ANY problem, don't you think they would be doing that?
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They really should have, but this is understandable. Old vector formats are always a security nightmare
- The original parsers / renderers where written on single user systems and focussed on rendering speed. They didn't anticipate hostile files.
- The original developers are long gone.
- EMF files were never popular on websites.
I would argue that their real mistake was adding EMF / WMF support to IE in the first place. It made sense to developers because it was only a few lines of code, but it was a terrible decision for security.
- The original parsers / renderers where written on single user systems and focussed on rendering speed. They didn't anticipate hostile files.
- The original developers are long gone.
- EMF files were never popular on websites.
I would argue that their real mistake was adding EMF / WMF support to IE in the first place. It made sense to developers because it was only a few lines of code, but it was a terrible decision for security.
EMF/WMF is especially bad because it is basically just a command language that gives direct access to GDI syscalls. It should just be considered excutable.
For a large part this is really old, badly written code that is scary to clean up because the functionality is underspecified. A lot of programs that Microsoft wants to continue working depend on weird features in it.
Google seems to have embarked on a mission to find vulnerabilities in everything that touches the Internet. Good for them (free marketing), good for us.
Forming an opinion about Microsoft vs. Google software quality would require knowing how many similar problems Microsoft found and subsequently patched in their software. Without that data, we can't tell whether Microsoft isn't putting effort into finding vulnerabilities in its software, or whether Google simply got lucky and found something Microsoft missed.
Forming an opinion about Microsoft vs. Google software quality would require knowing how many similar problems Microsoft found and subsequently patched in their software. Without that data, we can't tell whether Microsoft isn't putting effort into finding vulnerabilities in its software, or whether Google simply got lucky and found something Microsoft missed.
> Google seems to have embarked on a mission to find vulnerabilities in everything that touches the Internet. Good for them (free marketing), good for us.
And perhaps scaremongerings us to embrace the cloud, and thus ChromeOS...
And perhaps scaremongerings us to embrace the cloud, and thus ChromeOS...
In this specific case, this is a valid question: this is round 2 after MS already got the notification they need to fix this issue. Google is back with a specific proof-of-concept after giving Microsoft a high-level description of how to find and fix this vulnerability.
As part of MS16-074, some of the bugs were indeed fixed, such as the EMR_STRETCHBLT record, which the original proof-of-concept image relied on. However, we've discovered that not all of the DIB-related problems are gone.
As part of MS16-074, some of the bugs were indeed fixed, such as the EMR_STRETCHBLT record, which the original proof-of-concept image relied on. However, we've discovered that not all of the DIB-related problems are gone.
Companies tend not to publicly brag about it when they find bugs in their own code.
Patching 0-day issues usually is not hard in itself. Usually it is just little errors like missing checks for buffer overflows, or some input not sanitized. What is hard is making sure that everything still works after the patch. And "everything" is quite a lot in the case of this issue (gdi32.dll). You have to make sure that all still supported software depending on gdi32.dll is still working as it should, that includes multiple Windows versions, multiple Office versions, multiple Internet Explorer versions, multiple ... you get the idea. Microsoft has a lot of products.
Not saying that I don't admire this, but I don't know if any company would be willing to install "some patch" by "someone" with no guarantee that it won't break other things or open other holes. I would always want to install an official patch by an official vendor because I have support and warranty.
If we're talking about some legacy software with no support and no vendor taking care of updates - this is something I could get behind and I think is useful.