Hello and welcome to Programming Thursdays! Today, we’ll be diving into the world of C++ programming language. As a red teamer and pen tester, having a solid grasp of programming concepts and syntax is crucial. In this article, we’ll cover the basics of C++ as well as how it can be used for pen testing and red teaming. So grab your favorite caffeinated beverage and let’s get started!
C++ Basics
C++ is an object-oriented programming language that was first released in 1985. It was designed to improve on the C programming language by adding features such as classes, templates, and inheritance. C++ is widely used in a variety of applications, including operating systems, video games, and financial systems.
C++ Syntax
C++ is a powerful programming language that is widely used in software development, including pen testing and red teaming. In this section, we will cover some of the basic concepts of C++.
Variables and Constants
- Declare a variable:
int x = 5; - Declare a constant:
const int y = 10; - Change the value of a variable:
x = 7; - Constants cannot be changed:
// y = 20; // This line would cause a compile-time error because y is a constant
Data Types
- int:
int x = 5; - double:
double y = 3.14; - char:
char c = 'a'; - bool:
bool b = true; - string:
std::string s = "hello";
Arrays and Dictionaries
Declare an array:
int arr[5] = {1, 2, 3, 4, 5};Declare a dictionary:
std::unordered_map<std::string, int> dict = { {"apple", 1}, {"banana", 2}, {"orange", 3} };Access an array element:
arr[2]Access a dictionary element:
dict["banana"]
Functions
Declare a function:
int add(int a, int b);Define a function:
int add(int a, int b) { return a + b; }Call a function:
int result = add(2, 3);Return a value from a function:
return a + b;
Control Flow
if statement:
if (x > 0) { std::cout << "x is positive" << std::endl; }for loop:
for (int i = 0; i < 5; i++) { std::cout << i << std::endl; }while loop:
while (x < 10) { x++; }switch statement:
switch (x) { case 0: std::cout << "x is zero" << std::endl; break; case 1: std::cout << "x is one" << std::endl; break; default: std::cout << "x is not zero or one" << std::endl; break; }
The basic syntax of C++ is similar to that of C. C++ code is compiled into machine code, which can be run directly on a computer. Here’s an example of a “Hello, World!” program in C++:
#include <iostream>
int main() {
std::cout << "Hello, World!" << std::endl;
return 0;
}
Let’s break down this code:
#include <iostream>: This line includes the input/output library, which contains the std::cout function we’ll be using to print our message to the console.int main(): This line declares the main function, which is the entry point for the program.{}: These curly braces define the scope of the main function.std::cout << "Hello, World!" << std::endl;: This line prints the message “Hello, World!” to the console using thestd::coutfunction. The<<operator is used to concatenate multiple strings together, andstd::endlis used to add a newline character to the end of the message.return 0;: This line returns a value of 0 to indicate that the program executed successfully. Now that we’ve covered the basics of C++ syntax, let’s dive into how it can be used for pen testing and red teaming.
Pen Testing and Red Teaming with C++
C++ is a powerful programming language that can be used to develop tools for pen testing and red teaming. In this section, we’ll cover three examples: a port scanner, a password cracker, and a web crawler.
Port Scanner
A port scanner is a tool used to scan a network for open ports. This is useful for identifying potential vulnerabilities in a network. Here’s an example of a port scanner written in C++:
#include <iostream>
#include <cstdlib>
#include <string>
#include <cstring>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
int main(int argc, char *argv[]) {
if (argc < 2) {
std::cout << "Usage: " << argv[0] << " <hostname>" << std::endl;
return 1;
}
const char* hostname = argv[1];
struct hostent* host = gethostbyname(hostname);
if (host == nullptr) {
std::cout << "Could not resolve hostname: " << hostname << std::endl;
return 1;
}
for (int port = 1; port <= 65535; port++) {
int socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if (socket_fd < 0) {
std::cout << "Error creating socket" << std::endl;
return 1;
}
struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port);
memcpy(&server_addr.sin_addr.s_addr, &host->h_addr_list[0], host->h_length);
int result = connect(socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
if (result == 0) {
std::cout << "Port " << port << " is open" << std::endl;
}
close(socket_fd);
}
return 0;
}
This port scanner now loops over all ports from 1 to 65535 and attempts to connect to each one using the TCP protocol. If a connection is successful, it prints a message indicating that the port is open. Note that this approach can be slow, as it will try to connect to every port, even if most of them are closed. A more efficient approach would be to use multithreading to scan multiple ports simultaneously.
Password Cracker
A password cracker is a tool used to guess passwords by trying different combinations of characters. This can be useful for testing the strength of passwords on a system. Here’s an example of a password cracker written in C++:
#include <iostream>
#include <cstring>
#include <algorithm>
bool check_password(const char* password) {
// TODO: Implement password checking logic
return false;
}
void brute_force_password(const char* charset, size_t length) {
char* password = new char[length + 1];
memset(password, 0, length + 1);
while (true) {
if (check_password(password)) {
std::cout << "Password found: " << password << std::endl;
break;
}
size_t i = 0;
while (true) {
if (i == length) {
break;
}
if (password[i] == charset[strlen(charset) - 1]) {
password[i] = charset[0];
i++;
} else {
password[i] = charset[strchr(charset, password[i]) - charset + 1];
break;
}
}
}
delete[] password;
}
int main() {
const char* charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
size_t length = 8;
brute_force_password(charset, length);
return 0;
}
This password cracker uses a brute force method to try every possible combination of characters in a given character set up to a specified length. Let’s break down the code:
bool check_password(const char* password): This function checks if the provided password is correct. In a real-world password cracker, this function would be replaced with code that actually attempts to log in with the guessed password.void brute_force_password(const char* charset, size_t length): This function generates all possible passwords up to the specified length and checks them using the check_password function.char* password = new char[length + 1];: This line creates a new character array to hold the password.while (true): This line starts an infinite loop that generates passwords until a correct password is found.if (check_password(password)): This line checks if the current password is correct using the check_password function.size_t i = 0;: This line initializes a counter for the password length.while (true): This line starts an infinite loop that generates the next password.if (i == length): This line checks if the password has reached the maximum length. If so, the loop exits and the next password is checked.if (password[i] == charset[strlen(charset) - 1]): This line checks if the current character is the last character in the character set. If so, it resets the character to the first character and increments the counter.password[i] = charset[strchr(charset, password[i]) - charset + 1];: This line increments the current character to the next character in the character set.const char* charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";: This line defines the character set to be used for the password cracker.size_t length = 8;: This line defines the maximum length of the generated passwords.
Web Crawler
A web crawler is a tool used to automatically navigate and collect data from websites. This can be useful for finding vulnerabilities in web applications. Here’s an example of a web crawler written in C++:
#include <iostream>
#include <cstring>
#include <curl/curl.h>
size_t write_callback(char* ptr, size_t size, size_t nmemb, void* userdata) {
std::string* data = reinterpret_cast<std::string*>(userdata);
data->append(ptr, size * nmemb);
return size * nmemb;
}
int main(int argc, char *argv[]) {
if (argc < 2) {
std::cout << "Usage: " << argv[0] << " <url>" << std::endl;
return 1;
}
CURL* curl = curl_easy_init();
if (curl == nullptr) {
std::cout << "Error initializing curl" << std::endl;
return 1;
}
curl_easy_setopt(curl, CURLOPT_URL, argv[1]);
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
std::string response_data;
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_data);
CURLcode result = curl_easy_perform(curl);
if (result != CURLE_OK) {
std::cout << "Error performing curl request: " << curl_easy_strerror(result) << std::endl;
return 1;
}
std::cout << "Response data: " << std::endl << response_data << std::endl;
curl_easy_cleanup(curl);
return 0;
}
This web crawler takes a URL as a command line argument and retrieves the contents of that URL using the libcurl library. Let’s break down the code:
size_t write_callback(char* ptr, size_t size, size_t nmemb, void* userdata): This callback function is called by libcurl to process the data received from the HTTP request.std::string* data = reinterpret_cast<std::string*>(userdata);: This line casts the userdata pointer to a std:: string* so that the received data can be appended to it.curl_easy_setopt(curl, CURLOPT_URL, argv[1]);: This line sets the URL to retrieve.curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);: This line enables following HTTP redirects.curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);: This line sets the callback function to be called with the received data.curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_data);: This line sets the userdata pointer to be passed to the callback function.CURLcode result = curl_easy_perform(curl);: This line performs the HTTP request.std::cout << "Response data: " << std::endl << response_data << std::endl;: This line displays the received data.
Pros and Cons of C++ for Pen Testers and Red Team Members
C++ has several advantages and disadvantages for pen testers and red team members.
Pros
- Performance: C++ is a compiled language, which means it can be optimized for performance. This can be important when developing tools that need to be run quickly.
- Portability: C++ can be compiled for a variety of platforms, which makes it a good choice for developing cross-platform tools.
- Low-level control: C++ provides direct access to low-level system resources, which can be useful for developing tools that interact with the operating system or hardware.
Cons
- Steep learning curve: C++ has a complex syntax and can be difficult to learn for beginners.
- Memory management: C++ requires manual memory management, which can be error-prone and lead to memory leaks or buffer overflows.
- Lack of built-in networking and threading support: C++ does not have built-in support for networking or threading, which can make it more difficult to develop tools that require these features.
Conclusion
C++ is a powerful programming language that can be used for pen testing and red teaming. It provides low-level control and high performance, but can be difficult to learn and requires manual memory management. With the examples provided in this article, you should have a good starting point for developing your own tools in C++. So go forth and hack with confidence!