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Comment by wetw0rk | Hacker News Reader

If you’re following my Windows Kernel Exploitation series the time to bypass modern mitigations is now.

We’ve learned how to exploit a Stack Overflow in Windows 7 (x86) but what has changed since then?

Truthfully a lot, but the core fundamental problem exists and as such we as hackers will always find a way to exploit them.

As part of this tutorial, I will be releasing my technique on bypassing SMEP and VBS I have dubbed Violet Phosphorous. I personally have not seen these mitigations bypassed in this manner so I’m claiming it.

To prove its effectiveness, I installed the latest Windows 11 (x64) build (24H2) and successfully elevated my privileges to NT AUTHORITY/SYSTEM.

The king is dead, long live the king!

LONG LIVE THE STACK OVERFLOW!

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Super interesting. At one point thought control flow guard + DEP/ASLR was suppose to prevent this stuff, guess it can't be prevented nearly completely by now. Sounds like this took a lot of work to figure out, well done.

Any comment on reporting to Microsoft or perhaps motivation for this research?

So called "post-exploit" mitigations are practically always only hardening, i.e. making subsequent attacks harder (and fewer). Ideally much harder. But if you want an absolutely, provably (within limits, i.e. halting problem etc.) secure system, you have to eliminate bugs that can lead to any exploitable situations beforehand. In this case for example, that would mean no situation existing that could cause a buffer overflow in the first place. Memory-safe languages help for this case.

Obviously this is hard, so post-exploit mitigations will likely continue to still make things harder for attackers for quite a while at least.

Capabilities (as implemented in e.g. seL4) is the way to go.

Capabilities are a better security model, but don't protect you from kernel bugs. Provably correct kernels (such as seL4) do.

Having said that, being a microkernel, seL4 ends up pushing a bunch of potentially buggy code to use space. There are real benefits to that, but if you can exploit the page table server, the system is pretty much yours.

(This text was originally part of https://news.ycombinator.com/item?id=42353276 but that got killed by HN's software (bad), so I moved it here to the live post.)

Was your test install also fully updated, i.e. is your exploit currently valid?

Yes the violet phosphorus technique works on the default configuration of the latest build :)

>LONG LIVE THE STACK OVERFLOW!

The mitigation known as Shadow Stack might have something to say here.

Gonna have to give it a proper read-through over the weekend, but this looks like a stellar guide at a glance. Sincere thanks for sharing your work and looking forward to further entries in the series!

Thank you!

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