utils.h

#include <math.h>

const char* _version = "0.0.6";
const char* _banner = 
"  __________________ .____                               .__                  \n"
" /   _____/\\_   ___ \\|    |   _____   __ __  ____   ____ |  |__   ___________ \n"
" \\_____  \\ /    \\  \\/|    |   \\__  \\ |  |  \\/    \\_/ ___\\|  |  \\_/ __ \\_  __ \\\n"
" /        \\\\     \\___|    |___ / __ \\|  |  /   |  \\  \\___|   Y  \\  ___/|  | \\/\n"
"/_______  / \\______  /_______ (____  /____/|___|  /\\___  >___|  /\\___  >__|   \n"
"        \\/         \\/        \\/    \\/           \\/     \\/     \\/     \\/       \n\nVersion: %s\t\t\t\t\t\twww.thecyberyeti.com\n\n";

void usage(void) {
	puts("[~] Simple shellcode debugger and PE file wrapper!");
	puts("[~] Usage: sclauncher.exe [-f=shellcode.bin] [-o=INT] [-bp]");
    puts("");
    puts("[*] Global arguments:");
	puts("\t-f: [REQUIRED] path to file to load shellcode");
    puts("\t-ep: adjust entry point offset in bytes based on zero-index. Value can be base 10 or hex (prefix with 0x)");
    puts("");
    puts("[*] Debugging shellcode:");
    puts("\t-bp: insert a breakpoint before the shellcode");
    puts("\t-pause: Pause before execution, allowing time to attach a debugger");
    puts("\t-d: path to file to load additional content into memory, simply copies file content into new memory allocation");
    puts("\t\t-mm: memory map additional content, must be used with -d argument");
	puts("");
	puts("[*] Creating PE file:");
    puts("\t-pe: [REQUIRED] creates an executable version of the shellcode in a PE file");
    puts("\t-d: path to file to load additional content, content will be added to a new section in the PE file");
	puts("\t-64: creates a 64-bit PE file - assumes 64-bit shellcode");
    puts("\t-o: output file name");
    
}

void banner() {
    system("cls");
    printf(_banner, _version);
}

char* validate_argument(char*arg){
	char*p = NULL;
	p = strstr(arg,"=");
	if (p == NULL){
		printf("[!] Equal sign between \"%s\" parameter not found, exiting!",arg);
		exit(1);
	}
	p++;
	return p;
}

double calculate_entropy(unsigned char* shellcode, int shellcode_size) {
    // using shorts in case an individual byte values in encountered more than a byte can hold
    short prob[256] = {0};
    int i = 0;
    double entropy = 0;
    double p = 0;

    for(i=0; i < shellcode_size; i++) {
        prob[shellcode[i]]++;
    }

    for(i=0; i<256; i++){
        if (prob[i] != 0){
            p = (double)prob[i] / (double)shellcode_size;
            entropy -= p * log2(p);
        }
    }
    return entropy;
}