Security Practices

Spring Security Configuration

@Configuration
@EnableWebSecurity
class SecurityConfig {
    @Bean
    fun securityFilterChain(http: HttpSecurity): SecurityFilterChain = http
        .csrf { it.disable() }  // disable for API-only services
        .sessionManagement { it.sessionCreationPolicy(SessionCreationPolicy.STATELESS) }
        .authorizeHttpRequests {
            it.requestMatchers("/actuator/health/**").permitAll()
            it.requestMatchers("/api/v1/**").authenticated()
            it.anyRequest().denyAll()
        }
        .oauth2ResourceServer { it.jwt { } }
        .build()
}

Parameterized Queries — ALWAYS

// GOOD — parameterized
@Query("SELECT o FROM Order o WHERE o.customerId = :customerId")
fun findByCustomerId(@Param("customerId") customerId: String): List<Order>

// NEVER — string concatenation (SQL injection!)
"SELECT * FROM orders WHERE customer_id = '$customerId'"  // FATAL SECURITY BUG

Input Validation

data class CreateOrderRequest(
    @field:NotBlank val customerId: String,
    @field:NotEmpty val items: List<@Valid OrderItemRequest>,
    @field:Size(max = 500) val notes: String? = null
)

@PostMapping("/orders")
fun createOrder(@Valid @RequestBody request: CreateOrderRequest): ResponseEntity<Order> { ... }

Secret Management

• NEVER hardcode credentials in source code
• Use environment variables: ${DB_PASSWORD}, ${API_KEY}
• Use Spring @ConfigurationProperties to bind env vars
• Rotate secrets regularly
• .gitignore all .env, *.key, *.pem, credentials.json files

OWASP Top 10 Checklist

1. Injection → Parameterized queries only
2. Broken Auth → OAuth2/JWT, no custom auth
3. Sensitive Data → Encrypt at rest/transit, never log secrets
4. XXE → Disable external entity processing
5. Broken Access Control → Role-based + resource-level checks
6. Misconfiguration → Security headers, disable unused endpoints
7. XSS → Content-Type headers, input sanitization
8. Insecure Deserialization → Whitelist allowed types
9. Known Vulnerabilities → Regular dependency scanning
10. Insufficient Logging → Audit all auth events