Use when adding auth, handling input, creating endpoints, or dealing with secrets.
-
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);
}
}
-
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();
}
}
-
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));
}
-
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);
-
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));
}
-
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));
-
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}
-
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()));
-
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\"}");
}
}
}
