Crate uwd 

uwd 🦀

uwd is a Rust library for call stack spoofing on Windows, allowing you to execute arbitrary functions with a forged call stack that evades analysis, logging, or detection during stack unwinding.

Inspired by SilentMoonwalk, this crate brings low-level spoofing capabilities into a clean, idiomatic Rust interface with full support for #[no_std], MSVC and GNU toolchains, and automated gadget resolution.

Features

• ✅ Call stack spoofing via Synthetic and Desync.
• ✅ Compatible with both MSVC and GNU toolchains (x64).
• ✅ Inline macros: spoof! / syscall!.
• ✅ Supports #[no_std] environments (with alloc).

To enable Desync mode, activate the desync feature in your project, the macros will automatically use Desync behavior when the feature is enabled.

Getting started

Add uwd to your project by updating your Cargo.toml:

cargo add uwd

Usage

uwd allows you to spoof the call stack in Rust when calling either standard Windows APIs or performing indirect syscalls. The library handles the full setup of fake frames, gadget chains, and register preparation to make execution appear as if it came from a legitimate source.

You can spoof:

• Normal functions (like VirtualAlloc, WinExec, etc.)
• Native syscalls with automatic SSN and stub resolution (like NtAllocateVirtualMemory)

Spoofing WinExec

This example shows how to spawn calc.exe using a spoofed call stack. We call WinExec twice once using the Desync technique, and again using the Synthetic one.

use dinvk::{GetModuleHandle, GetProcAddress};
use uwd::spoof;

// Resolves addresses of the WinAPI functions to be used
let kernel32 = GetModuleHandle("kernel32.dll", None);
let win_exec = GetProcAddress(kernel32, "WinExec", None);

// Execute command with `WinExec`
let cmd = c"calc.exe";
let mut result = spoof!(win_exec, cmd.as_ptr(), 1)?;
if result.is_null() {
    eprintln!("WinExec Failed");
    return Ok(());
}

Spoofing an Indirect Syscall

This example performs a indirect system call to NtAllocateVirtualMemory with a spoofed call stack.

use std::{ffi::c_void, ptr::null_mut};
use dinvk::NT_SUCCESS;
use uwd::{syscall, AsPointer};

// Running indirect syscall with Call Stack Spoofing
let mut addr = null_mut::<c_void>();
let mut size = (1 << 12) as usize;
let mut status = syscall!("NtAllocateVirtualMemory", -1isize, addr.as_ptr_mut(), 0, size.as_ptr_mut(), 0x3000, 0x04)? as i32;
if !NT_SUCCESS(status) {
    eprintln!("[-] NtAllocateVirtualMemory Failed With Status: {status:#X}");
    return Ok(())
}

println!("[+] Address allocated: {:?}", addr);

Additional Resources

For more examples, check the examples folder in the repository.

References

I want to express my gratitude to these projects that inspired me to create uwd and contribute with some features:

• SilentMoonwalk

Special thanks to:

• Kudaes
• Klez
• Waldo-IRC
• Trickster0
• namazso

License

This project is licensed under the MIT License. See the LICENSE file for details.

Modules

internal

Internal module responsible for executing call stack spoofing.

Macros

spoof

Invokes the function using a synthetic stack layout.

syscall

Wraps a native Windows syscall with a simulated stack layout.

Enums

SpoofKind

Specifies the type of spoof being performed

Traits

AsPointer

Trait for casting references to raw c_void pointers.

Functions

ignoring_set_fpreg

Calculates the total stack frame size of a function, ignoring setfp frames.

rbp_offset

Checks if the RBP register is pushed or saved on the stack in a spoofable manner.

stack_frame

Calculates the stack size of a function and checks if it uses RBP as frame pointer.