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kevoreilly / capemon

capemon: CAPE's monitor
GNU General Public License v3.0
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Question : API covered by capemon #19

Closed 3ntr0phy closed 3 years ago

3ntr0phy commented 3 years ago

I have a simple question. Does capemon cover the whole set of Windows API or only a subset of them? Thank you

kevoreilly commented 3 years ago

A subset. The APIs are listed in hooks.h: https://github.com/kevoreilly/capemon/blob/capemon/hooks.h

3ntr0phy commented 3 years ago

Out of curiosity : why this design choice? There is any rationale for not log all of them?

kevoreilly commented 3 years ago

The number of exported functions in ntdll alone is > 2000, not far off 2000 in kernelbase, then there is kernel32. That's not even getting started on networking APIs. The total number in the Windows API? I am guessing many tens if not hundreds of thousands of functions. To hook them all would require work in writing hooks, which can also be technically challenging. The output from all these hooks would be massive so would slow down processing and mean interesting stuff in the logs would be drowned out by uninteresting info. Then there is the increased risk of bugs... All lead to the question of why one would want to hook everything?

3ntr0phy commented 3 years ago

Thank you for the reply :) I am mainly referring to the following syscalls : https://github.com/j00ru/windows-syscalls Probably there was a misunderstanding, I used API and should have used syscalls !

kevoreilly commented 3 years ago

I see what you mean - capemon's hooks are of course not true syscall hooks. But assuming each true syscall is wrapped by a function exported by ntdll, then it would be possible to hook those functions. I think the reason this hasn't been done is just that some syscalls aren't that useful from the perspective of malware analysis.

As an aside I have been experimenting with 'nirvana' hooks in win10 which is a true syscall hooking mechanism - maybe one day I'll publish this if it's reliable enough.

3ntr0phy commented 3 years ago

What do you mean not true syscall hooks?

Do you mean this hooking mechanism https://infocondb.org/con/recon/recon-2015/hooking-nirvana-stealthy-instrumentation-techniques-for-windows-10 ?

3ntr0phy commented 3 years ago

Not sure anyway, sempahore syscalls may be interesting as well for example...

kevoreilly commented 3 years ago

In general, I just mean a technique that hooks the actual syscall mechanism, so each time the syscall instruction is executed it is hooked. In capemon it's a user-mode hook of a user-mode wrapper for a syscall. So, for example, direct syscalls to NtAllocateVirtualMemory will not be captured with capemon hook on the exported function from ntdll of the same name.