Implementation of secure authentication mechanisms to prevent unauthorized access using Pass The Hash technique.
import javax.servlet.http.*;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class PassTheHashServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
String passwordHash = request.getParameter("passwordHash");
String username = request.getParameter("username");
if (authenticate(username, passwordHash)) {
HttpSession session = request.getSession();
session.setAttribute("username", username);
response.sendRedirect("secureArea.jsp");
} else {
response.sendRedirect("login.jsp");
}
}
private boolean authenticate(String username, String passwordHash) {
String storedPasswordHash = getPasswordHashFromDatabase(username);
return storedPasswordHash.equals(passwordHash);
}
private String getPasswordHashFromDatabase(String username) {
// This is a placeholder. In a real application, you would retrieve the hash from the database.
return "5f4dcc3b5aa765d61d8327deb882cf99";
}
}
The above code demonstrates a security vulnerability known as 'Pass the Hash'. In this code, a servlet receives a username and a password hash from the client-side and uses these to authenticate the user.
The
doPost method retrieves the password hash and username from the request parameters. It then calls the
authenticate method, which compares the received password hash with the one stored in the database for the given username. If the hashes match, the method returns
true and the user is authenticated.
The vulnerability lies in the fact that the system is authenticating users based on the password hash rather than the password itself. This means that an attacker who has somehow obtained the hash of a user's password can authenticate themselves as that user simply by sending the hash. They don't need to know the actual password.
This is a serious security risk as password hashes can often be obtained from data breaches, phishing attacks, or other hacking techniques. Once an attacker has a password hash, they can potentially gain access to all resources within the domain that the user has access to.
In addition, the system does not implement any form of hash salting. Salt is random data that is used as an additional input to a one-way function that hashes data, a password or passphrase. Salts are used to safeguard passwords in storage, and they do this by adding additional random data to the input of a hash function that hashes a password. The benefit provided by using a salted password (or 'salting' a password) is that it adds further security to encrypted data (stored passwords), by protecting against dictionary attacks or attacks that use rainbow tables.
To fix this vulnerability, the system should be modified to authenticate users based on their actual password, not the hash. Furthermore, the system should implement a secure password hashing algorithm that includes a unique salt for each user.
import javax.servlet.http.*;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Base64;
public class SecureAuthenticationServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
String password = request.getParameter("password");
String username = request.getParameter("username");
if (authenticate(username, password)) {
HttpSession session = request.getSession();
session.setAttribute("username", username);
response.sendRedirect("secureArea.jsp");
} else {
response.sendRedirect("login.jsp");
}
}
private boolean authenticate(String username, String password) {
String storedPasswordHash = getPasswordHashFromDatabase(username);
String salt = getSaltFromDatabase(username);
String hashedPassword = hashPassword(password, salt);
return storedPasswordHash.equals(hashedPassword);
}
private String hashPassword(String password, String salt) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256");
md.update(salt.getBytes());
byte[] bytes = md.digest(password.getBytes());
return Base64.getEncoder().encodeToString(bytes);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
}
}
private String getPasswordHashFromDatabase(String username) {
// This is a placeholder. In a real application, you would retrieve the hash from the database.
return "5f4dcc3b5aa765d61d8327deb882cf99";
}
private String getSaltFromDatabase(String username) {
// This is a placeholder. In a real application, you would retrieve the salt from the database.
return "somesalt";
}
}
The updated code now implements a secure authentication mechanism that does not rely on passing the hash. Instead, it uses a strong hashing algorithm (SHA-256) to hash the password provided by the user during authentication. This hashed password is then compared with the hashed password stored in the database.
The password is salted before hashing. The salt is a random string that is unique for each user and is stored in the database along with the hashed password. Salting the password before hashing adds an extra layer of security by making it more difficult for an attacker to use precomputed tables (rainbow tables) to crack the password.
The servlet also implements secure session management. After the user is authenticated, a new session is created and the username is stored in the session. This prevents session hijacking by ensuring that the session ID cannot be predicted.
The application should be served over a secure communication protocol (e.g., HTTPS) to protect sensitive data during transmission. This is not shown in the code, as it is typically configured in the web server or application server hosting the application.
Finally, it is important to regularly update and patch the application and its dependencies to address any security vulnerabilities. This includes updating the Java Development Kit (JDK) to the latest version, updating the servlet container (e.g., Apache Tomcat), and updating any libraries used by the application.