springboot-security

name	springboot-security
description	Spring Security best practices for authn/authz, validation, CSRF, secrets, and rate limiting. Use when adding auth, handling input, or securing Spring Boot endpoints.
origin	MCC

Spring Boot Security Review

Use when adding auth, handling input, creating endpoints, or dealing with secrets.

When to Activate

• Adding authentication (JWT, OAuth2, session-based)
• Implementing authorization (@PreAuthorize, role-based access)
• Validating user input (Bean Validation, custom validators)
• Configuring CORS, CSRF, or security headers
• Managing secrets (Vault, environment variables)
• Adding rate limiting or brute-force protection
• Scanning dependencies for CVEs

Authentication

• Prefer stateless JWT or opaque tokens with revocation list
• Use httpOnly, Secure, SameSite=Strict cookies for sessions
• Validate tokens with OncePerRequestFilter or resource server

@Component
public class JwtAuthFilter extends OncePerRequestFilter {
  private final JwtService jwtService;

  public JwtAuthFilter(JwtService jwtService) {
    this.jwtService = jwtService;
  }

  @Override
  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
      FilterChain chain) throws ServletException, IOException {
    String header = request.getHeader(HttpHeaders.AUTHORIZATION);
    if (header != null && header.startsWith("Bearer ")) {
      String token = header.substring(7);
      Authentication auth = jwtService.authenticate(token);
      SecurityContextHolder.getContext().setAuthentication(auth);
    }
    chain.doFilter(request, response);
  }
}

Authorization

• Enable method security: @EnableMethodSecurity
• Use @PreAuthorize("hasRole('ADMIN')") or @PreAuthorize("@authz.canEdit(#id)")
• Deny by default; expose only required scopes

@RestController
@RequestMapping("/api/admin")
public class AdminController {

  @PreAuthorize("hasRole('ADMIN')")
  @GetMapping("/users")
  public List<UserDto> listUsers() {
    return userService.findAll();
  }

  @PreAuthorize("@authz.isOwner(#id, authentication)")
  @DeleteMapping("/users/{id}")
  public ResponseEntity<Void> deleteUser(@PathVariable Long id) {
    userService.delete(id);
    return ResponseEntity.noContent().build();
  }
}

Input Validation

• Use Bean Validation with @Valid on controllers
• Apply constraints on DTOs: @NotBlank, @Email, @Size, custom validators
• Sanitize any HTML with a whitelist before rendering

// BAD: No validation
@PostMapping("/users")
public User createUser(@RequestBody UserDto dto) {
  return userService.create(dto);
}

// GOOD: Validated DTO
public record CreateUserDto(
    @NotBlank @Size(max = 100) String name,
    @NotBlank @Email String email,
    @NotNull @Min(0) @Max(150) Integer age
) {}

@PostMapping("/users")
public ResponseEntity<UserDto> createUser(@Valid @RequestBody CreateUserDto dto) {
  return ResponseEntity.status(HttpStatus.CREATED)
      .body(userService.create(dto));
}

SQL Injection Prevention

• Use Spring Data repositories or parameterized queries
• For native queries, use :param bindings; never concatenate strings

// BAD: String concatenation in native query
@Query(value = "SELECT * FROM users WHERE name = '" + name + "'", nativeQuery = true)

// GOOD: Parameterized native query
@Query(value = "SELECT * FROM users WHERE name = :name", nativeQuery = true)
List<User> findByName(@Param("name") String name);

// GOOD: Spring Data derived query (auto-parameterized)
List<User> findByEmailAndActiveTrue(String email);

Password Encoding

• Always hash passwords with BCrypt or Argon2 — never store plaintext
• Use PasswordEncoder bean, not manual hashing

@Bean
public PasswordEncoder passwordEncoder() {
  return new BCryptPasswordEncoder(12); // cost factor 12
}

// In service
public User register(CreateUserDto dto) {
  String hashedPassword = passwordEncoder.encode(dto.password());
  return userRepository.save(new User(dto.email(), hashedPassword));
}

CSRF Protection

• For browser session apps, keep CSRF enabled; include token in forms/headers
• For pure APIs with Bearer tokens, disable CSRF and rely on stateless auth

http
  .csrf(csrf -> csrf.disable())
  .sessionManagement(sm -> sm.sessionCreationPolicy(SessionCreationPolicy.STATELESS));

Secrets Management

• No secrets in source; load from env or vault
• Keep application.yml free of credentials; use placeholders
• Rotate tokens and DB credentials regularly

# BAD: Hardcoded in application.yml
spring:
  datasource:
    password: mySecretPassword123

# GOOD: Environment variable placeholder
spring:
  datasource:
    password: ${DB_PASSWORD}

# GOOD: Spring Cloud Vault integration
spring:
  cloud:
    vault:
      uri: https://vault.example.com
      token: ${VAULT_TOKEN}

Security Headers

http
  .headers(headers -> headers
    .contentSecurityPolicy(csp -> csp
      .policyDirectives("default-src 'self'"))
    .frameOptions(HeadersConfigurer.FrameOptionsConfig::sameOrigin)
    .xssProtection(Customizer.withDefaults())
    .referrerPolicy(rp -> rp.policy(ReferrerPolicyHeaderWriter.ReferrerPolicy.NO_REFERRER)));

CORS Configuration

• Configure CORS at the security filter level, not per-controller
• Restrict allowed origins — never use * in production

@Bean
public CorsConfigurationSource corsConfigurationSource() {
  CorsConfiguration config = new CorsConfiguration();
  config.setAllowedOrigins(List.of("https://app.example.com"));
  config.setAllowedMethods(List.of("GET", "POST", "PUT", "DELETE"));
  config.setAllowedHeaders(List.of("Authorization", "Content-Type"));
  config.setAllowCredentials(true);
  config.setMaxAge(3600L);

  UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
  source.registerCorsConfiguration("/api/**", config);
  return source;
}

// In SecurityFilterChain:
http.cors(cors -> cors.configurationSource(corsConfigurationSource()));

Rate Limiting

• Apply Bucket4j or gateway-level limits on expensive endpoints
• Log and alert on bursts; return 429 with retry hints

// Using Bucket4j for per-endpoint rate limiting
@Component
public class RateLimitFilter extends OncePerRequestFilter {
  private final Map<String, Bucket> buckets = new ConcurrentHashMap<>();

  private Bucket createBucket() {
    return Bucket.builder()
        .addLimit(Bandwidth.classic(100, Refill.intervally(100, Duration.ofMinutes(1))))
        .build();
  }

  @Override
  protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
      FilterChain chain) throws ServletException, IOException {
    String clientIp = request.getRemoteAddr();
    Bucket bucket = buckets.computeIfAbsent(clientIp, k -> createBucket());

    if (bucket.tryConsume(1)) {
      chain.doFilter(request, response);
    } else {
      response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
      response.getWriter().write("{\"error\": \"Rate limit exceeded\"}");
    }
  }
}

Dependency Security

• Run OWASP Dependency Check / Snyk in CI
• Keep Spring Boot and Spring Security on supported versions
• Fail builds on known CVEs

Logging and PII

• Never log secrets, tokens, passwords, or full PAN data
• Redact sensitive fields; use structured JSON logging

File Uploads

• Validate size, content type, and extension
• Store outside web root; scan if required

Checklist Before Release

• Auth tokens validated and expired correctly
• Authorization guards on every sensitive path
• All inputs validated and sanitized
• No string-concatenated SQL
• CSRF posture correct for app type
• Secrets externalized; none committed
• Security headers configured
• Rate limiting on APIs
• Dependencies scanned and up to date
• Logs free of sensitive data

Remember: Deny by default, validate inputs, least privilege, and secure-by-configuration first.