Go-Shellcode : A Repository Of Windows Shellcode Runners And Supporting Utilities

Go-Shellcode is a repository of Windows Shellcode runners and supporting utilities. The applications load and execute Shellcode using various API calls or techniques.

The available Shellcode runners include:

CreateFiber

This application leverages the Windows CreateFiber function from the Kernel32.dll to execute shellcode within this application’s process. This is usefull when you want to avoid remote process injection and want to avoid calling CreateThread. This application DOES NOT leverage functions from the golang.org/x/sys/windows package. The most significant difference is that this application loads all the necessary DLLs and Procedures itself and uses the procedure’s Call() function.

NOTE: I have not figured out way to have the process exit and you will have to manually terminate it.

The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateFiber.exe .\cmd\CreateFiber\main.go

CreateProcess

This application leverages the Windows CreateProcess function from Kernel32.dll. The process is created in a suspended state, the AddressOfEntryPoint in the IMAGE_OPTIONAL_HEADER structure is updated to execute shellcode in the childprocess, and then the process is resumed. This is a type of process hollowing but the existing PE is NOT unmapped and the ThreadContext is NOT updated. The provided shellcode architecture (i.e. x86 or x64) must match the architecture of the child process.

The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateProcess.exe .\cmd\CreateProcess\main.go

CreateProcessWithPipe

This application leverages the Windows CreateProcess function from Kernel32.dll. The process is created in a suspended state, the AddressOfEntryPoint in the IMAGE_OPTIONAL_HEADER structure is updated to execute shellcode in the childprocess, and then the process is resumed. This is a type of process hollowing but the existing PE is NOT unmapped and the ThreadContext is NOT updated. The provided shellcode architecture (i.e. x86 or x64) must match the architecture of the child process.

This application differs from CreateProcess because it will collect any data written to STDOUT or STDERR in the child process and return it to the parent process. Data is collected by using the CreatePipe function to create an anonymous pipe that the parent and child process communicate over. This is usefull when using tools like Donut to execute a .NET assembly in a child process as shellcode and to retrieve the output of the executed program. The following command can be used to generate position-independent shellcode to run Seatbelt with Donut v0.9.3:

.\donut.exe -o donut_v0.9.3_Seatbelt.bin -x 2 -c Seatbelt.Program -m Main -p "ARPTable" Seatbelt.exe

The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateProcessWithPipe.exe .\cmd\CreateProcessWithPipe\main.go

CreateRemoteThread

This application leverages the Windows CreateRemoteThread function from Kernel32.dll to execute shellocde in a remote process. The application requires that the target process to inject into is already running. The targe Process Identifier (PID) can provided at runtime for testing using the -pid command line flag. Hardcode the PID in the following line of code for operational use by replacing the 0 with your target PID:

pid := flag.Int("pid", 0, "Process ID to inject shellcode into")

This application leverages functions from the golang.org/x/sys/windows package, where feasible, like the windows.OpenProcess(). The application can be compiled wit the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateRemoteThread.exe .\cmd\CreateRemoteThread\main.go

CreateRemoteThreadNative

This application leverages the Windows CreateRemoteThread function from Kernel32.dll to execute shellocde in a remote process. The application requires that the target process to inject into is already running. The targe Process Identifier (PID) can provided at runtime for testing using the -pid command line flag. Hardcode the PID in the following line of code for operational use by replacing the 0 with your target PID:

pid := flag.Int("pid", 0, "Process ID to inject shellcode into")

This application DOES NOT leverage functions from the golang.org/x/sys/windows package. The most significant difference is that this application loads all the necessary DLLs and Procedures itself and uses the procedure’s Call() function. The application can be compiled with the following command on Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateRemoteThreadNative.exe .\cmd\CreateRemoteThreadNative\main.go

CreateThread

This application leverages the Windows CreateThread function from Kernel32.dll to execute shellcode within this application’s process. This is usefull when you want to avoid remote process injection. This application leverages functions from the golang.org/x/sys/windows package, where feasible, like the windows.VirtualAlloc()`. The application can be compiled with the following command on Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateThread.exe .\cmd\CreateThread\main.go

CreateThreadNative

This application leverages the Windows CreateThread function from the Kernel32.dll to execute shellcode within this application’s process. This is usefull when you want to avoid remote process injection. This application DOES NOT leverage functions from the golang.org/x/sys/windows package. The most significant difference is that this application loads all the necessary DLLs and Procedures itself and uses the procedure’s Call() function. The application can be compiled with the following command on Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o CreateThreadNative.exe .\cmd\CreateThreadNative\main.go

EarlyBird

The application leverages the Windows CreateProcess function to create a process in a suspended state. Once the child process is suspended, the Windows QueueUserAPC function is used to add a UserAPC to the child process that points to the allocate shellcode. Next, ResumeThread is called, which subsequently calls the undocumented NtTestAlert function that will execute the created UserAPC and in turn the shellcode. This is usefull because the shellcode will execute before AV/EDR can hook functions to support detection. Reference New ‘Early Bird’ Code Injection Technique Discovered. The application can be compiled with the following command on Windows host from the project’s root directory:

export GOOS=windows GOARCH=amd64;go build -o goEarlyBird.exe cmd\EarlyBird\main.go

EtwpCreateEtwThread

This application leverages the Windows EtwpCreateEtwThread function from ntdll.dll to execute shellcode within this application’s process. Original work by TheWover. This is usefull when you want to avoid remote process injection. This application DOES NOT leverage functions from the golang.org/x/sys/windows package. The most significant difference is that this application loads all the necessary DLLs and Procedures itself and uses the procedure’s Call() function. The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o EtwpCreateEtwThread.exe .\cmd\EtwpCreateEtwThread\main.go

NtQueueApcThreadEx (local)

This application uses the undocumented NtQueueApcThreadEx to create a “Special User APC” in the current thread of the current process to execute shellcode. Because the shellcode is loaded and executed in the current process, it is “local”. This same technique can be used for a remote process. NOTE: This will only work on Windows 7 or later. Reference APC Series: User APC API.

export GOOS=windows GOARCH=amd64;go build -o goNtQueueApcThreadEx-Local.exe cmd\NtQueueApcThreadEx-Local\main.go

RtlCreateUserThread

This application leverages the Windows RtlCreateUserThread function from ntdll.dll to execute shellocde in a remote process. The application requires that the target process to inject into is already running. The targe Process Identifier (PID) can provided at runtime for testing using the -pid command line flag. Hardcode the PID in the following line of code for operational use by replacing the 0 with your target PID:

pid := flag.Int("pid", 0, "Process ID to inject shellcode into")

This application DOES NOT leverage functions from the golang.org/x/sys/windows package. The most significant difference is that this application loads all the necessary DLLs and Procedures itself and uses the procedure’s Call() function. The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o RtlCreateUserThread.exe .\cmd\RtlCreateUserThread\main.go

Syscall

This application executes Shellcode in the current running proccess by making a Syscall on the Shellcode’s entry point. This application DOES NOT leverage functions from the golang.org/x/sys/windows package. The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o Syscall.exe .\cmd\Syscall\main.go

UuidFromStringA

This application leverages the Windows UuidFromStringA function to load shellcode to a memory address and then calls the EnumSystemLocalesA function to execute the shellcode. This method of loading and executing shellcode was derived from nccgroup’s RIFT: Analysing a Lazarus Shellcode Execution Method. For this application, memory is allocated on the heap and it does not use VirtualAlloc. The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o UuidFromString.exe .\cmd\UuidFromString\main.go

ShellcodeUtils

This application is used to transform shellcode binary files. The program depends that the input file is a binary file (.bin) that contains the hex bytes of the shellcode. ShellcodeUtils can just base64 encode your input file or it can XOR, RC4, or AES256-GCM encrypt it. The tools can also be used to decrypt files as well.

ShellcodeUtils help menu:

-base64
Base64 encode the output. Can be used with or without encryption
-i string
Input file path of binary file
-key string
Encryption key
-mode string
Mode of operation to perform on the input file encrypt,decrypt
-nonce string
Nonce, in hex, used to decrypt an AES256 input file. Only used during decryption
-o string
Output file path
-salt string
Salt, in hex, used to generate an AES256 32-byte key through Argon2. Only used during decryption
-type string
The type of encryption to use [xor, aes256, rc4, null]
-v Enable verbose output

Example of only Base64 encoding the input file and saving it a text file:

PS C:\Users\bob> .\ShellcodeUtils.exe -i C:\Users\bob\calc.bin -o C:\Users\bob\calc.b64.txt -base64 -v
[-]Output directory: C:\Users\bob\
[-]Output file name: calc.b64.txt
[-]File contents (hex): 505152535657556a605a6863616c6354594883ec2865488b32488b7618488b761048ad488b30488b7e3003573c8b5c17288b741f204801fe8b541f240fb72c178d5202ad813c0757696e4575ef8b741f1c4801fe8b34ae4801f799ffd74883c4305d5f5e5b5a5958c3
[-]No encryption type provided, continuing on…
[+]Output (string):
UFFSU1ZXVWpgWmhjYWxjVFlIg+woZUiLMkiLdhhIi3YQSK1IizBIi34wA1c8i1wXKIt0HyBIAf6LVB8kD7csF41SAq2BPAdXaW5Fde+LdB8cSAH+izSuSAH3mf/XSIPEMF1fXltaWVjD
[+] encrypt input and wrote 140 bytes to: C:\Users\bob\calc.b64.txt

Example XOR encrypting input file with a key of Sh3!1z AND base64 encoding the output:

PS C:\Users\bob> .\ShellcodeUtils.exe -i C:\Users\bob\calc.bin -o C:\Users\bob\calc.xor.b64.txt -mode encrypt -type xor -key Sh3!1z -v
[-]Output directory: C:\Users\bob\
[-]Output file name: calc.xor.b64.txt
[-]File contents (hex): 505152535657556a605a6863616c6354594883ec2865488b32488b7618488b761048ad488b30488b7e3003573c8b5c17288b741f204801fe8b541f240fb72c178d5202ad813c0757696e4575ef8b741f1c4801fe8b34ae4801f799ffd74883c4305d5f5e5b5a5958c3
[-]XOR encrypting input file with key: Sh3!1z
[+]Output (hex):
03396172672d0602537b5919320450756832d0841b4479f16120b8572932d81e23699c32d8587baa4f4a503f0faa6d6d7be3473e11325296b8752e5e5cdf1f36bc2851c5b21d362d3a067654def127772f693084d85c9d69308dca97e469b2be63356c7f6a200a30f0
[+]xor encrypt input and wrote 105 bytes to: C:\Users\bob\calc.xor.b64.txt

Example AES256-GCM encrypting the input file with a password of Sh3!1z WITHOUT base64 encoding the ouput:

PS C:\Users\bob> .\ShellcodeUtils.exe -i C:\Users\bob\calc.bin -o C:\Users\bob\calc.aes.bin -mode encrypt -type aes256 -key Sh3!1z -v
[-]Output directory: C:\Users\bob\
[-]Output file name: calc.aes.bin
[-]File contents (hex): 505152535657556a605a6863616c6354594883ec2865488b32488b7618488b761048ad488b30488b7e3003573c8b5c17288b741f204801fe8b541f240fb72c178d5202ad813c0757696e4575ef8b741f1c4801fe8b34ae4801f799ffd74883c4305d5f5e5b5a5958c3
[-]AES256 encrypting input file
[+]Argon2 salt (hex): db6126d3ac640f8aaa67cda74b8cf1d2c54513db7bf4fbe3422d1b276af1367e
[+]AES256 key (32-bytes) derived from input password Sh3!1z (hex): 096a40f1aef38dd9b5d63284acc19727c4420dd98f21ea052112bef63eb7d94a
[+]AES256 nonce (hex): 13802153c4b2fb6a3e545ff4
[+]Output (hex):
44a974233e37b460dc2181b16846f265e8e3a07959abf9c8760f7d0ac8029575e67571ea5b313bc8b011739db57c690ec156a4b0bba4e4d632c35c1490aeaac24f5ae05e90934adf57798ee3c702a3c27073fe976fbcc6ee5db355da186c1add58913e41a8c5716a0fcfc27371f0cae906e50e680366496a00
[+]aes256 encrypt input and wrote 121 bytes to: C:\Users\bob\calc.aes.bin

AES256 requires a 32-byte key. This program uses the Argon2 ID algorithm to take the password provided with the -key input paramter to derive a 32-byte key while using a randomly generate salt. You will need the same input password and the salt used with the Argon2 algorithm and the same nonce used with the AES256 algorithm to successfull decrypt the file. Alternatively, the decryption function could be updated to just use the 32-byte Argon2 key instead of the input password and salt.

NOTE: It is up to the operator to decide to just use the generated Argon2 key or to use the password and salt that are used to generate the password.

Example AES256 decrypting the input file:

PS C:\Users\bob> .\ShellcodeUtils.exe -i C:\Users\bob\calc.aes.bin -o C:\Users\bob\calc.aes.decrypted.bin -mode decrypt -type aes256 -key Sh3!1z -nonce 13802153c4b2fb6a3e545ff4 -salt db6126d3ac640f8aaa67cda74b8cf1d2c54513db7bf4fbe3422d1b276af1367e -v
[-]Output directory: C:\Users\bob\
[-]Output file name: calc.aes.decrypted.bin
[-]File contents (hex): 44a974233e37b460dc2181b16846f265e8e3a07959abf9c8760f7d0ac8029575e67571ea5b313bc8b011739db57c690ec156a4b0bba4e4d632c35c1490aeaac24f5ae05e90934adf57798ee3c702a3c27073fe976fbcc6ee5db355da186c1add58913e41a8c5716a0fcfc27371f0cae906e50e680366496a00
[-]AES256 decrypting input file
[-]Argon2 salt (hex): db6126d3ac640f8aaa67cda74b8cf1d2c54513db7bf4fbe3422d1b276af1367e
[-]AES256 key (hex): 096a40f1aef38dd9b5d63284acc19727c4420dd98f21ea052112bef63eb7d94a
[-]AES256 nonce (hex): 13802153c4b2fb6a3e545ff4
[+]Output (hex):
505152535657556a605a6863616c6354594883ec2865488b32488b7618488b761048ad488b30488b7e3003573c8b5c17288b741f204801fe8b541f240fb72c178d5202ad813c0757696e4575ef8b741f1c4801fe8b34ae4801f799ffd74883c4305d5f5e5b5a5958c3
[+]aes256 decrypt input and wrote 105 bytes to: C:\Users\bob\calc.aes.decrypted.bin

The application can be compiled with the following command on a Windows host from the project’s root directory:

set GOOS=windows GOARCH=amd64;go build -o ShellcodeUtils.exe .\cmd\ShellcodeUtils\main.go