superdong/hellgateloader_csharp

Load shelcode via HELLGATE, rewrite hellgate for learning purpose.

HellgateLoader_CSharp

Blog link: working on it

• Base on the original Hellgate project down below:

  1. https://github.com/am0nsec/SharpHellsGate
  2. https://github.com/am0nsec/HellsGate

• And my other project down below:

  1. SysCall_ShellcodeLoader
  2. HookDetection
  3. DInvoke_ShellcodeLoader
  4. NewNtdllBypassInlineHook

• I make this project for learning purpose, use it at you own risk.

• Only tested it on Win10/x64 works fine.

• For better understanding, you really need to read the PDF(https://vxug.fakedoma.in/papers/VXUG/Exclusive/HellsGate.pdf) from the original author.

• Thanks to them I do learn a lot, during code this project.

• Also, there is a little different here, Instead of read the syscall id from the memory, I read 24 bytes as the syscall， so you don‘t need to concat them again. I think that would be more convenient for me.

• (From the PDF)This general usage code base self-resolves syscalls without the need for static elements. Additionally, this general usage code base makes zero function invocations to aggregate the syscalls themselves.

• About how it works:

  1. Read the ntdll.dll via IO.stream from disk as MemoryStream.
  2. Find the RVA of function address.
  3. Convert the rva to file offset(RVA - IMAGE_SECTION_HEADER_instance.VirtualAddress + IMAGE_SECTION_HEADER_instance.PointerToRawData;).
  4. Use the offset to find to function offset in MemoryStream.
  5. Read 24 bytes as syscall from MemoryStream with the right offset.
  6. Execute the syscall via delegate.

• The picture down below helps you to understand file offset.

• The code from the original project is elegant as hell, guess that is why is called HELLGATE :) :) ~

• You could even modify the code to like injection or something else.

Usage

1. Set the APIs name that you need in "SyscallTable.cs" ,In this case is: v1.Name = "NtAllocateVirtualMemory"; v2.Name = "NtCreateThreadEx"; v3.Name = "NtWaitForSingleObject";

2. Set the shellcode in Program.cs, the default shellcode is a Calc.

TO-DO list

• Works on both x64/x86
• Restructure the code

Update history

• NONE

Reference link:

1. https://github.com/am0nsec/HellsGate
2. https://github.com/am0nsec/SharpHellsGate
3. https://vxug.fakedoma.in/papers/VXUG/Exclusive/HellsGate.pdf 
4. https://docs.microsoft.com/zh-cn/dotnet/api/system.reflection.bindingflags?view=net-5.0
5. https://docs.microsoft.com/zh-cn/dotnet/api/system.runtime.compilerservices.runtimehelpers.preparemethod?view=net-5.0
6. https://docs.microsoft.com/zh-cn/dotnet/api/system.runtime.compilerservices.runtimehelpers.preparemethod?redirectedfrom=MSDN&view=net-5.0#System_Runtime_CompilerServices_RuntimeHelpers_PrepareMethod_System_RuntimeMethodHandle_System_RuntimeTypeHandle___
7. https://docs.microsoft.com/zh-cn/dotnet/api/system.runtime.interopservices.marshal.allochglobal?view=net-5.0
8. https://www.cnblogs.com/qintangtao/archive/2013/01/11/2857180.html
9. https://blog.csdn.net/StriveScript/article/details/6279488
10. https://www.cnblogs.com/wyping/p/3643243.html
11. https://blog.csdn.net/e295166319/article/details/52702461
12. https://blog.csdn.net/qiqi5045/article/details/7736576
13. https://blog.csdn.net/tianxiayijia1998/article/details/50119435
14. https://www.runoob.com/csharp/csharp-generic.html
15. https://www.csharpcodi.com/csharp-examples/System.RuntimeMethodHandle.GetFunctionPointer()/
16. https://cloud.tencent.com/developer/article/1015264
17. https://a1ex.online/2020/07/26/PE-to-LoadLibrary-md/
18. https://www.displayfusion.com/Discussions/View/converting-c-data-types-to-c/?ID=38db6001-45e5-41a3-ab39-8004450204b3