https://github.com/Maldev-Academy/HellHall

Performing Indirect Clean Syscalls
https://github.com/Maldev-Academy/HellHall

edrs syscalls

Last synced: about 2 months ago
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Performing Indirect Clean Syscalls

• Host: GitHub
• URL: https://github.com/Maldev-Academy/HellHall
• Owner: Maldev-Academy
• Created: 2023-01-03T04:43:05.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2023-04-19T06:10:47.000Z (over 1 year ago)
• Last Synced: 2024-06-11T03:34:32.484Z (3 months ago)
• Topics: edrs, syscalls
• Language: C
• Size: 29.3 KB
• Stars: 421
• Watchers: 7
• Forks: 61
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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• awesome-edr-bypass - Maldev-Academy/HellHall: Performing Indirect Clean Syscalls

README

        
## HellsHall - Another Way To Fetch Clean Syscalls

HellsHall is a combination of [HellsGate](https://github.com/am0nsec/HellsGate) and indirect syscalls.  




## How it works

First, HellsHall checks whether the *syscall address* is hooked and tries to retrieve the syscall number by checking the presence of the following bytes: 

`0x4C, 0x8B, 0xD1, 0xB8` which represent `mov r10,rcx && mov eax,SSn`. This is how every syscall should start.

At this point, HellsGate simply grabs the Syscall SSn (Syscall Number) and uses it **directly** resulting in a syscall being called from outside of the address space of `ntdll.dll`. This is an IoC in itself and can be used to detect such syscalls. Detection Examples:

* [Detecting Manual Syscalls from User Mode](https://winternl.com/detecting-manual-syscalls-from-user-mode/)

* [Detecting Direct Syscalls with Frida](https://passthehashbrowns.github.io/detecting-direct-syscalls-with-frida)

HellsHall however will search for a `syscall` instruction near the address of the syscall function and then save this *syscall's instruction's address* to a global variable which will be jumped to later on rather than executing this instruction directly from the `asm` file. This will cause the syscall function to be executed from inside of `ntdll.dll` address space with the only difference being that it's unhooked.

## Enhancement

[TartarusGate](https://github.com/trickster0/TartarusGate) can be used to further enhance this technique.




## HellsGate

![image](https://user-images.githubusercontent.com/111295429/210207400-594383fb-158f-415c-9e3a-2d3d43198644.png)




## HellsHall

![image](https://user-images.githubusercontent.com/111295429/210207411-f6dca820-dbfe-4c87-bb33-60e0d036bd73.png)




## Profit

Bypassing The Below EDR using [This HellsHall Implementation](https://github.com/Maldev-Academy/HellHall/blob/main/Hell'sHall-Clang%26NoCrt.zip) That is Using `NtAllocateVirtualMemory`, `NtProtectVirtualMemory`, and `NtCreateThreadEx` syscalls with an `RWX` section. 

![image](https://user-images.githubusercontent.com/111295429/210299245-d366566a-0e14-4622-8bb0-91fd645a9d2e.png)




## Code

The Github repo can be found [here](https://github.com/Maldev-Academy/HellHall)




## Authors

* NULL (@NUL0x4C)

* mr.d0x (@mrd0x)