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Lazarus and the FudModule rootkit: Beyond BYOVD with an admin-to-kernel zero-day (avast.io)
76 points by LinuxBender 10 months ago | hide | past | favorite | 19 comments



I feel like they are applying the Lazarus group name to a wide variery of NK related groups. This is way beyond what i've seen/heard them do. I beleive much of lazarus is security/pentesr guys that have legit outfits in China and SE asia that moonlight for NK.


Man although I know nothing about this kind of stuffs I still enjoy very much reading it. Great writeup!

This is the kind of work that I look forward to doing.


That’s a really good write up, with lots of details and pointers to other interesting sources to dig into.


These guys are quite talented.


Not a vulnerability, as admin generally has the same privileges as kernel. At best this is a mitigation bypass.

From the article:

> Microsoft’s security servicing criteria have long asserted that “[a]dministrator-to-kernel is not a security boundary”


This isn't Linux. On windows admin means admin, not super user. And kernel mode is accesible only to signed drivers unless driver signing is disabled (bad idea outside of driver dev labs).

Admin -> SYSTEM while not always easy, it isn't a security boundary per-se. but SYSTEM -> kernel, there is a very well established security boundary. For example, being able to uninstall a security tool like crowdstrike falcon without an uninstall code even as admin or SYSTEM is considered a CVE if you can manage to do so. But there are tools that exploit driver vulns to and can kill EDRs like falcon from kernel mode.

With win11+ BYOVD should be a lot harder and I'm curious if even in kernel mode if a virtualization based security boundary can be kept such as LSA isolation (default in win11, optional/off in win 10).


> is considered a CVE

for crowdstrike falcon I imagine.

> SYSTEM -> kernel, there is a very well established security boundary

Not according to the Microsoft there is not. Really this should be the end of discussion. https://www.microsoft.com/en-us/msrc/windows-security-servic...

For funsies. https://devblogs.microsoft.com/oldnewthing/20221004-00/?p=10...


Yikes... In the same doc:

>"For example, the separation between kernel mode and user mode is a classic and straightforward security boundary."

>"Non-boundaries: [...] Administrator to Kernel [...] Administrative processes and users are considered part of the Trusted Computing Base (TCB) for Windows and are therefore not strong isolated from the kernel boundary."

The reasoning makes sense, but that's quite a mixed message for an unintuitive nuance.


What do you mean "unintuitive"? Administrator is the owner of the machine. They can do whatever they want.


I think that used to be correct, but stopped being true around windows XP.

Before that, Administrator was the same as unix root: A person capable to administer the system for all other users.

But the average end user was not interested or capable to do the job, the computer was now personal so there were no other users, and driver manufacturers were simply not good at their job. Additionally, DRM implies you're not allowed to have full ownership of a machine anymore.

Microsoft, sick of receiving the misery of other people's incompetence and smelling DRM dollars, hollowed out Administrator. They kept the account name, as power users would rebel otherwise, but a new layer on top was created.

The almost reached conclusion: If you force it hard enough, you can gain system and kernel access, but secure boot will make sure you lose DRM at that point.

An exploit like this is why I still can say: almost.


You have no clue what are you talking about. The official documentation is linked and even quoted above. I'm impressed people can't grasp that simple statement even on this forum.


Thanks for your kind words.

The old new thing is not very relevant for this discussion, so let's focus on the first, the 'Microsoft Security Servicing Criteria for Windows'.

This document lists when microsoft promises to fix a security vulnerability, and when they will pay out a bounty. No more, no less. By it's nature, this document is minimalist, and won't promise anything not strictly necesarry. Notice at the bottom of the document a whole list of Defense in depth features (e.g. DEP) falling outside these criteria. As they were implemented, Microsoft clearly does see value in them, even if they won't promise anything about fixing them.

So yes, an admin elevating to system and then kernel has no automatic intent to service in their security vision and is not bounty eligible.

But nothing of all this conflicts with anything in the post above. I presume microsoft will fix DRM problems. They will make life hard for people running things inside the kernel with no signature. They will annoy you if you pirate windows. None if these fall under the scope of the document.

Compare it to the current edge/bing situation. An admin can remove them from the system. But a next patch will ressurect them. Microsoft will wear you down, even if they made a promise about it.


You are just blubbing about DRM. It is irrelevant to the discussed issue. Security wise this is not a severe issue if an issue at all.

> Thanks for your kind words.

You get what you deserve for unapologetically repeating false statements already rebutted above in the very same thread with info from the primary source.


If you can bypass driver signing it's not a legit MS bug?? Bounty or not, driver signature enforcement is a security boundary, features like secureboot are invalid if an os malware can just load boot time drivers of its own.


... omg. Just stop. You are wrong in the SAME way over again. This bug does not let you bypass secure boot. The point of bypassing secure boot is gaining administrative privileges on the system, usually to access encrypted files. If you already have that privilege, you already crossed that boundary.


One has to assume that NK is using its most promising students for two things:

- Cyber warfare and theft

- Furthering its nuclear and missile programs


Instead of using them for finance and making people click on ads…


Not that much anymore, more likely working on warfare killing robots now, and ICBMs like SpaceX.

So something in common.





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