OWASP API Security Top 2: Broken Authentication and How to Handle It in Spring Boot 3.x

In today’s interconnected world, APIs are the backbone of modern applications, enabling communication between services. However, with great connectivity comes great responsibility — particularly in securing these APIs against potential threats. The OWASP API Security Top 10 lists the most critical vulnerabilities affecting APIs, with Broken Authentication ranking as the second most significant risk.

In this article, we’ll explore what Broken Authentication is, why it matters, and how you can prevent it in your Spring Boot 3.x applications using the latest security practices.

Understanding Broken Authentication

Broken Authentication refers to vulnerabilities that allow attackers to exploit authentication mechanisms to gain unauthorized access to an application. This can result from improper implementation of authentication functions, allowing attackers to:

• Compromise user credentials.
• Assume other users’ identities.
• Exploit session management flaws.

Example Scenarios:

• Weak Password Policies: Users can set simple passwords like “password123”.
• Credential Stuffing: Attackers use leaked credentials from other breaches to access user accounts.
• Session Hijacking: Session IDs are exposed or predictable, enabling attackers to impersonate users.
• Inadequate Token Expiration: Tokens do not expire or have excessively long lifespans.

Why Broken Authentication Matters

The consequences of Broken Authentication can be severe:

• Unauthorized Access: Attackers can gain access to sensitive data or functionalities.
• Account Takeover: Users lose control of their accounts, leading to potential data breaches.
• Data Theft: Personal information, financial data, and other sensitive information can be stolen.
• Reputation Damage: Security breaches can erode customer trust and damage brand reputation.
• Compliance Violations: Non-compliance with regulations like GDPR or CCPA can result in hefty fines.

Common Causes of Broken Authentication

1. Weak Password Policies: Allowing users to set weak or commonly used passwords.
2. Insecure Credential Storage: Storing passwords in plain text or using weak hashing algorithms.
3. Lack of Multi-Factor Authentication (MFA): Not providing an additional layer of security beyond passwords.
4. Predictable Session Tokens: Using session identifiers that are easy to guess.
5. Exposed Session IDs: Including session IDs in URLs or logs where they can be intercepted.
6. Improper Session Management: Failing to invalidate sessions upon logout or after a period of inactivity.
7. Brute Force Vulnerabilities: Not limiting the number of login attempts.

Preventing Broken Authentication in Spring Boot 3.x

Spring Boot 3.x, in combination with Spring Security 6.x, provides robust tools to implement secure authentication mechanisms. Let’s explore how to address common vulnerabilities.

1. Enforce Strong Password Policies

Implement password complexity requirements to prevent users from setting weak passwords.

Password Encoder Configuration:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;

@Configuration
public class SecurityConfig {

    // Define the password encoder bean
    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }
}

Explanation:

• BCryptPasswordEncoder: Uses the BCrypt hashing function, which is adaptive and includes a salt to protect against rainbow table attacks.
• Strength Parameter: You can adjust the strength (log rounds) if needed, but the default is sufficient for most applications.

2. Implement Multi-Factor Authentication (MFA)

Adding an extra layer of security makes it harder for attackers to compromise accounts.

Implementing MFA Steps:

1. User Login: User enters username and password.
2. Generate One-Time Password (OTP): Send an OTP via email or SMS.
3. Validate OTP: User enters the OTP to complete authentication.

Controller Example:

@RestController
@RequestMapping("/auth")
public class AuthenticationController {

    // Inject necessary services

    @PostMapping("/login")
    public ResponseEntity<?> login(@RequestBody LoginRequest loginRequest) {
        // Authenticate username and password
        // Generate OTP and send to user
        return ResponseEntity.ok("OTP sent to your email.");
    }

    @PostMapping("/verify-otp")
    public ResponseEntity<?> verifyOtp(@RequestBody OtpRequest otpRequest) {
        // Verify the OTP
        // Generate JWT or establish session
        return ResponseEntity.ok("Authentication successful.");
    }
}

Note: For production, use secure channels to send OTPs and consider time-based OTPs (TOTP) using apps like Google Authenticator.

3. Secure Session Management

Proper session management prevents session hijacking and fixation.

Session Configuration:

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.web.SecurityFilterChain;

@Configuration
public class SecurityConfig {

    // Other configurations...

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            // Other configurations...
            .sessionManagement(session -> session
                .sessionCreationPolicy(SessionCreationPolicy.IF_REQUIRED)
                .maximumSessions(1)
                .maxSessionsPreventsLogin(true)
            )
            .sessionFixation().migrateSession();
        return http.build();
    }
}

Explanation:

• sessionCreationPolicy: Controls when sessions are created.
• maximumSessions(1): Limits concurrent sessions per user.
• maxSessionsPreventsLogin(true): Prevents new logins when the maximum is reached.
• sessionFixation().migrateSession(): Replaces the session ID upon authentication to prevent session fixation.

4. Protect Against Brute Force Attacks

Implement mechanisms to limit repeated login attempts.

In-Memory Attempt Counter:

import org.springframework.stereotype.Service;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;

@Service
public class LoginAttemptService {

    private final int MAX_ATTEMPT = 5;
    private final long LOCK_TIME_DURATION = TimeUnit.MINUTES.toMillis(15);
    private ConcurrentHashMap<String, Integer> attemptsCache = new ConcurrentHashMap<>();
    private ConcurrentHashMap<String, Long> lockTimeCache = new ConcurrentHashMap<>();

    public void loginSucceeded(String key) {
        attemptsCache.remove(key);
        lockTimeCache.remove(key);
    }

    public void loginFailed(String key) {
        int attempts = attemptsCache.getOrDefault(key, 0);
        attempts++;
        attemptsCache.put(key, attempts);
        if (attempts >= MAX_ATTEMPT) {
            lockTimeCache.put(key, System.currentTimeMillis());
        }
    }

    public boolean isBlocked(String key) {
        if (lockTimeCache.containsKey(key)) {
            long lockTime = lockTimeCache.get(key);
            if (System.currentTimeMillis() - lockTime > LOCK_TIME_DURATION) {
                // Unlock the account after the lock time duration
                attemptsCache.remove(key);
                lockTimeCache.remove(key);
                return false;
            }
            return true;
        }
        return false;
    }
}

Integration in Authentication Provider:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.authentication.AuthenticationProvider;

public class CustomAuthenticationProvider implements AuthenticationProvider {

    @Autowired
    private LoginAttemptService loginAttemptService;

    @Override
    public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        String username = authentication.getName();

        if (loginAttemptService.isBlocked(username)) {
            throw new LockedException("Your account is locked due to multiple failed login attempts. Please try again later.");
        }

        // Perform authentication logic
        try {
            // If authentication succeeds
            loginAttemptService.loginSucceeded(username);
            // Return authenticated token
        } catch (BadCredentialsException e) {
            loginAttemptService.loginFailed(username);
            throw e;
        }
    }

    @Override
    public boolean supports(Class<?> authentication) {
        // Return true if this AuthenticationProvider supports the indicated Authentication object.
        return true;
    }
}

Explanation:

• LoginAttemptService: Tracks login attempts and locks accounts after exceeding the maximum attempts.
• Integration: The authentication provider uses this service to block authentication if necessary.

5. Secure Credential Storage

Always store passwords securely using strong hashing algorithms.

Using Argon2 Password Encoder:

import org.springframework.security.crypto.argon2.Argon2PasswordEncoder;

// In SecurityConfig class
@Bean
public PasswordEncoder passwordEncoder() {
    return Argon2PasswordEncoder.defaultsForSpringSecurity_v5_8();
}

Explanation:

• Argon2PasswordEncoder: Argon2 is a modern and secure password hashing algorithm.
• Defaults for Spring Security 5.8: Ensures compatibility and security best practices.

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6. Use HTTPS Everywhere

Ensure all communications are encrypted to prevent eavesdropping and man-in-the-middle attacks.

Enforce HTTPS in Application Properties:

server:
  ssl:
    enabled: true
    key-store: classpath:keystore.p12
    key-store-password: yourpassword
    key-store-type: PKCS12
  port: 8443

Redirect HTTP to HTTPS:

import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
import org.springframework.stereotype.Component;

@Component
public class ServerPortCustomizer
  implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {

    @Override
    public void customize(ConfigurableServletWebServerFactory factory) {
        factory.setPort(8080); // HTTP port
    }
}

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;

@Configuration
public class SecurityConfig {

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http) throws Exception {
        http
            // Other configurations...
            .requiresChannel(channel -> channel
                .anyRequest().requiresSecure()
            );
        return http.build();
    }
}

Explanation:

• SSL Configuration: Enables HTTPS with provided keystore.
• Redirect Configuration: Forces all requests to use HTTPS.

7. Implement Account Lockout Mechanisms

Lock accounts after a predefined number of failed login attempts to prevent brute force attacks.

Using Spring Security Event Listeners:

import org.springframework.context.ApplicationListener;
import org.springframework.security.authentication.event.AuthenticationFailureBadCredentialsEvent;
import org.springframework.stereotype.Component;

@Component
public class AuthenticationFailureListener implements ApplicationListener<AuthenticationFailureBadCredentialsEvent> {

    @Autowired
    private LoginAttemptService loginAttemptService;

    @Override
    public void onApplicationEvent(AuthenticationFailureBadCredentialsEvent event) {
        String username = (String) event.getAuthentication().getPrincipal();
        loginAttemptService.loginFailed(username);
    }
}

Explanation:

• AuthenticationFailureListener: Listens for authentication failure events to track failed attempts.
• Integration with LoginAttemptService: Updates the attempt counter upon failure.

Best Practices

• Use Strong Password Policies: Enforce minimum length, complexity, and disallow common passwords.
• Implement MFA: Add layers of security beyond just passwords.
• Secure Session IDs: Use cryptographically secure random session identifiers.
• Token Expiration: Ensure tokens and sessions expire appropriately.
• Monitor and Log Authentication Events: Keep detailed logs for auditing and detecting suspicious activities.
• Avoid Exposing Session IDs: Do not include session IDs in URLs or logs.
• Regularly Update Dependencies: Keep libraries and frameworks up to date to incorporate security patches.
• Educate Users: Encourage users to use unique passwords and be aware of phishing attempts.
• Penetration Testing: Regularly test your application for vulnerabilities.

Conclusion

Broken Authentication is a critical vulnerability that can have devastating effects on your application and users. By leveraging the robust features provided by Spring Boot 3.x and Spring Security 6.x, you can implement strong authentication mechanisms to protect against these threats.

Remember that security is not a one-time setup but an ongoing process. Stay informed about the latest security practices, regularly update your dependencies, and continuously monitor your applications for potential vulnerabilities.

By taking these proactive steps, you can significantly reduce the risk of Broken Authentication and enhance the overall security posture of your applications.

References

• OWASP API Security Top 10
• Spring Security Reference Documentation
• Spring Boot Reference Documentation
• Argon2 Password Hashing
• NIST Digital Identity Guidelines
• Using Argon2 in Spring Security