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Comment by sst8 | Hacker News Reader

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.

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> 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.

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.

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.

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.

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.

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)

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.

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.

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