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ShellcodeLoader.cpp
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170 lines (136 loc) · 8.84 KB
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// ShellcodeLoader.cpp: define el punto de entrada de la aplicación de consola.
//
#include "stdafx.h"
using namespace std;
void parse_args(pProgramArgs args, int argc, const char** argv)
{
string userInput;
// make a new ArgumentParser
ArgumentParser parser;
parser.appName("ShellcodeLoader");
// add arguments
parser.addArgument("-e", "--entrypoint", 1, 1);
parser.addArgument("-a", "--address", 1, 1);
parser.addArgument("-r", "--run");
parser.addArgument("-b", "--break");
parser.addFinalArgument("file");
// parse the command-line arguments - throws if invalid format
parser.parse(argc, argv);
// retrieve the argument values
if (parser.exists("e") || parser.exists("entrypoint")) {
args->offset = stol(parser.retrieve<string>("entrypoint"), 0, 16);
}
if (parser.exists("a") || parser.exists("address")) {
args->preferredAddress = stoll(parser.retrieve<string>("address"), 0, 16);
}
if (parser.exists("r") || parser.exists("run")) {
args->nopause = true;
}
if (parser.exists("b") || parser.exists("break")) {
args->debug = true;
args->nopause = true;
}
// final argument
args->file = parser.retrieve<string>("file");
// check is there a debugger running
if (IsDebuggerPresent() && !args->debug && !args->nopause) {
cout << "[?] Debugger detected! Would you like to set a BP before execution? (y/n)" << endl;
getline(cin, userInput);
if (userInput == "y" || userInput == "Y") {
args->debug = true;
args->nopause = true;
}
}
}
int main(int argc, const char** argv)
{
ProgramArgs args = { "", 0, false, false, 0 };
char* printDirection;
FUNC code;
LPVOID memory = 0;
// hello message
system("cls");
cout << "Welcome to ShellcodeLoader!" << endl;
//Parse args
parse_args(&args, argc, argv);
// let's open the file
cout << "[+] Opening file: " << args.file << endl;
HANDLE handle = CreateFileA(args.file.c_str(), GENERIC_READ, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if (handle == INVALID_HANDLE_VALUE) {
cout << "[-] File doesn't exist" << endl;
return 2;
}
// get the file size
cout << "[+] Getting file size" << endl;
DWORD size = GetFileSize(handle, 0);
if (size <= 0) {
cout << "[-] Error reading size of file" << endl;
return 3;
}
// let's try to allocate memory in the specified address
if (args.preferredAddress != NULL) {
cout << "[+] Allocating space in preferred address: ";
cout << showbase << hex << args.preferredAddress;
cout << endl;
memory = VirtualAlloc((LPVOID)args.preferredAddress, size, 0x3000, 0x40);
if (memory == NULL) {
cout << "[-] Failed! Trying in another address..." << endl;
memory = VirtualAlloc(0, size, 0x3000, 0x40);
}
}
else {
cout << "[+] Allocating space in memory" << endl;
memory = VirtualAlloc(0, size, 0x3000, 0x40);
}
code = (FUNC)memory;
if (code == NULL) {
cout << "[-] Error allocating space" << endl;
return 4;
}
// read the file into memory
cout << "[+] Reading file into buffer" << endl;
DWORD bytesRead;
bool read = ReadFile(handle, code, size, &bytesRead, 0);
if (read == NULL) {
cout << "[-] Error reading file" << endl;
return 5;
}
// close the handle to the file
CloseHandle(handle);
// calc the entrypoint to the shellcode
printDirection = reinterpret_cast<char*>(code);
if (args.offset != NULL) {
printDirection += args.offset;
code = reinterpret_cast<FUNC>(printDirection);
}
cout << "[+] Entry point will be at address: ";
cout << showbase << hex << (long long) code;
cout << endl;
// stop debugger
if (!args.nopause) {
cout << "[+] Set a breakpoint to the Entry Point manually. Press any key to continue to the shellcode." << endl;
getchar();
}
// jump to shellcode
cout << "[+] JUMP AROUND!" << endl;
executeShellcode(args.debug, code);
// free the memory allocated for the shellcode
VirtualFree(memory, size, MEM_RELEASE);
cout << "[+] Execution finished. Press any key to quit" << endl;
getchar();
return 0;
}
int filter(unsigned int code, struct _EXCEPTION_POINTERS *ep) {
cout << "[!] Unhandled exception was generated during shellcode execution" << endl;
return EXCEPTION_EXECUTE_HANDLER;
}
void executeShellcode(bool debugging, FUNC shellcode) {
__try {
if (debugging) {
__debugbreak();
}
shellcode();
}
__except (filter(GetExceptionCode(), GetExceptionInformation())) {
}
}