Spring Security auto-configuration in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the default behavior of Spring Security auto-configuration in a new Spring Boot web app?

When you create a new Spring Boot web application and include Spring Security starter, what does the auto-configuration do by default?

A It disables security and allows all requests without authentication.

B It requires manual configuration to enable any security features.

C It secures only POST requests and allows GET requests without authentication.

D It secures all HTTP endpoints with basic authentication requiring a generated password.

💡 Hint

Think about what Spring Security does out of the box to protect your app.

By default, Spring Security auto-configuration secures all HTTP endpoints with basic authentication. It generates a default password printed in the console.

📝 Syntax

intermediate

Which code snippet correctly disables Spring Security auto-configuration in a Spring Boot app?

You want to disable Spring Security auto-configuration completely. Which of the following code snippets achieves this?

A @SpringBootApplication(exclude = SecurityAutoConfiguration.class)

B @EnableAutoConfiguration(include = SecurityAutoConfiguration.class)

C @SpringBootApplication(disable = SecurityAutoConfiguration.class)

D @EnableSecurityAutoConfiguration(false)

💡 Hint

Look for the annotation attribute that excludes auto-configuration classes.

Using @SpringBootApplication(exclude = SecurityAutoConfiguration.class) disables Spring Security auto-configuration.

❓ state_output

advanced

What is the value of the default generated password printed by Spring Security auto-configuration?

When Spring Security auto-configures your app, it prints a default password in the console. What is the format of this password?

A A random UUID string generated at startup.

B The fixed string 'password' for all apps by default.

C An empty string, meaning no password is set.

D The username repeated twice as the password.

💡 Hint

Check the console output when you run a Spring Boot app with Spring Security starter.

The default password is a random UUID string generated each time the app starts.

🧠 Conceptual

advanced

Which Spring Boot property disables the default security password generation?

You want to disable the default generated password and allow users to set their own. Which property disables the default password generation?

A spring.security.user.enabled=false

B spring.security.user.generate-password=false

C spring.security.user.password=

D spring.security.user.default-password=false

💡 Hint

Setting this property to an empty value disables the generated password.

Setting spring.security.user.password= disables the default generated password and requires you to set your own password.

❓ lifecycle

expert

In what order does Spring Security auto-configuration apply filters in the filter chain by default?

Spring Security auto-configuration sets up a filter chain for HTTP requests. Which of the following correctly describes the order of these filters?

A ExceptionTranslationFilter → FilterSecurityInterceptor → SecurityContextPersistenceFilter → BasicAuthenticationFilter

B SecurityContextPersistenceFilter → BasicAuthenticationFilter → ExceptionTranslationFilter → FilterSecurityInterceptor

C BasicAuthenticationFilter → SecurityContextPersistenceFilter → FilterSecurityInterceptor → ExceptionTranslationFilter

D FilterSecurityInterceptor → ExceptionTranslationFilter → BasicAuthenticationFilter → SecurityContextPersistenceFilter

💡 Hint

Think about how Spring Security manages context, authentication, exceptions, and authorization.

The correct filter order is: SecurityContextPersistenceFilter loads the security context, then BasicAuthenticationFilter processes login, ExceptionTranslationFilter handles exceptions, and FilterSecurityInterceptor enforces access control.

Practice

1. What happens when you add spring-boot-starter-security to a Spring Boot project without any additional configuration?

easy

A. The application runs without any security restrictions.

B. All web endpoints are secured with a default login page.

C. Only REST endpoints are secured, web pages remain open.

D. The application throws an error due to missing configuration.

Solution

1. Step 1: Understand default behavior of spring-boot-starter-security

   Adding this starter enables Spring Security auto-configuration which secures all web endpoints by default.

2. Step 2: Recognize the default login page

   Spring Security provides a default login page automatically when no custom security config is provided.

3. Final Answer:

   All web endpoints are secured with a default login page. -> Option B

4. Quick Check:

   Default security = secured endpoints + login page [OK]

Hint: Default security locks all endpoints with login page [OK]

Common Mistakes:

• Thinking endpoints remain open without config
• Assuming only REST endpoints are secured
• Believing an error occurs without config

2. Which of the following is the correct way to disable Spring Security auto-configuration in a Spring Boot application?

easy

A. @Configuration(exclude = SecurityAutoConfiguration.class)

B. @EnableAutoConfiguration(exclude = SecurityAutoConfiguration.class)

C. @ComponentScan(exclude = SecurityAutoConfiguration.class)

D. @SpringBootApplication(exclude = SecurityAutoConfiguration.class)

Solution

1. Step 1: Identify the correct annotation to exclude auto-configuration

   Spring Boot allows excluding auto-configurations via the exclude attribute in @SpringBootApplication.

2. Step 2: Confirm the correct class to exclude

   The class to exclude for disabling security auto-configuration is SecurityAutoConfiguration.class.

3. Final Answer:

   @SpringBootApplication(exclude = SecurityAutoConfiguration.class) -> Option D

4. Quick Check:

   Disable auto-config = exclude in @SpringBootApplication [OK]

Hint: Exclude SecurityAutoConfiguration in @SpringBootApplication [OK]

Common Mistakes:

• Using @EnableAutoConfiguration instead of @SpringBootApplication
• Trying to exclude in @ComponentScan or @Configuration
• Not specifying the correct class to exclude

3. Given this Spring Boot application with spring-boot-starter-security added and no custom security config, what will happen when a user accesses /hello endpoint?

 @RestController
 public class HelloController {
   @GetMapping("/hello")
   public String hello() {
     return "Hello World";
   }
 }

medium

A. The user sees "Hello World" without login.

B. The endpoint returns 404 Not Found.

C. The user is redirected to a login page before seeing "Hello World".

D. The application throws a runtime exception.

Solution

1. Step 1: Recall default security behavior with no custom config

   All endpoints are secured and require authentication by default.

2. Step 2: Understand access flow to /hello endpoint

   Accessing /hello triggers Spring Security to redirect to the default login page before allowing access.

3. Final Answer:

   The user is redirected to a login page before seeing "Hello World". -> Option C

4. Quick Check:

   Default security = login redirect before access [OK]

Hint: No config means login page before any endpoint access [OK]

Common Mistakes:

• Assuming endpoints are open without login
• Expecting 404 error for existing endpoint
• Thinking runtime exception occurs

4. You added spring-boot-starter-security but your application fails to start with a bean creation error related to AuthenticationManager. What is the likely cause?

medium

A. You defined a custom SecurityFilterChain but forgot to expose an AuthenticationManager bean.

B. You did not add spring-boot-starter-web dependency.

C. You excluded SecurityAutoConfiguration but still use security annotations.

D. You have multiple @SpringBootApplication classes.

Solution

1. Step 1: Understand the error context with AuthenticationManager bean

   When customizing security by defining a SecurityFilterChain, Spring Boot no longer auto-configures AuthenticationManager.

2. Step 2: Identify missing bean definition

   You must manually expose an AuthenticationManager bean to satisfy dependencies.

3. Final Answer:

   You defined a custom SecurityFilterChain but forgot to expose an AuthenticationManager bean. -> Option A

4. Quick Check:

   Custom filter chain needs AuthenticationManager bean [OK]

Hint: Custom SecurityFilterChain requires AuthenticationManager bean [OK]

Common Mistakes:

• Blaming missing web dependency
• Ignoring need for AuthenticationManager bean
• Assuming multiple @SpringBootApplication causes this error

5. You want to customize Spring Security auto-configuration to allow public access to /public/** endpoints but secure all others with form login. Which configuration snippet correctly achieves this?

hard

A. Define a SecurityFilterChain bean with http.authorizeHttpRequests().requestMatchers("/public/**").permitAll().anyRequest().authenticated().and().formLogin().

B. Exclude SecurityAutoConfiguration and manually configure WebSecurityConfigurerAdapter to permit /public/**.

C. Add @EnableWebSecurity and override configure(HttpSecurity http) to permit /public/** and disable form login.

D. Add @SpringBootApplication(exclude = SecurityAutoConfiguration.class) and use http.csrf().disable().

Solution

1. Step 1: Use SecurityFilterChain bean to customize security rules

   Spring Security 5.7+ recommends defining a SecurityFilterChain bean for custom rules.

2. Step 2: Permit /public/** and require authentication for others with form login

   The method chain authorizeHttpRequests().requestMatchers("/public/**").permitAll().anyRequest().authenticated().and().formLogin() correctly sets these rules.

3. Final Answer:

   Define a SecurityFilterChain bean with http.authorizeHttpRequests().requestMatchers("/public/**").permitAll().anyRequest().authenticated().and().formLogin() -> Option A

4. Quick Check:

   Permit public paths + secure others + form login = Define a SecurityFilterChain bean with http.authorizeHttpRequests().requestMatchers("/public/**").permitAll().anyRequest().authenticated().and().formLogin(). [OK]

Hint: Use SecurityFilterChain bean with permitAll and formLogin [OK]

Common Mistakes:

• Excluding auto-config and using deprecated WebSecurityConfigurerAdapter
• Disabling form login when it is required
• Misusing @EnableWebSecurity without proper bean