Not so fast- are you securing your swagger endpoints?
- Mark Kendall
- Feb 13
- 3 min read
You're right, exposing your entire API documentation through Swagger without any role-based access control is a significant security vulnerability. Even if your UI correctly restricts functionality based on roles, a determined user could bypass it by directly interacting with the API through Swagger. They could see all available endpoints and potentially even try to execute them.
Here's how you can address this on your Spring Boot backend:
1. Spring Security Integration with Swagger:
The most robust approach is to integrate Spring Security with your Swagger configuration. This allows you to leverage your existing role-based authentication and authorization mechanisms to control access to your Swagger UI and API documentation.
*Dependencies:** Ensure you have the necessary dependencies. You'll likely need `springdoc-openapi-starter-webmvc-api` (or a similar Swagger/OpenAPI library) and `spring-boot-starter-security`.
*Configuration:** You'll need to configure Spring Security to protect your Swagger endpoints. Here's a basic example:
```java
@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
// Whitelist Swagger resources and API documentation
.antMatchers("/v3/api-docs/**", "/swagger-ui/**", "/swagger-ui.html").permitAll()
// Secure other endpoints as needed (e.g., permitAll for login, authenticated for other endpoints)
.antMatchers("/api/**").authenticated() // Example: Require authentication for /api endpoints
.anyRequest().authenticated() // Or .anyRequest().permitAll() if you want everything authenticated
.and()
.httpBasic(); // Or formLogin(), oauth2Login(), etc. depending on your auth method
}
}
```
*Role-Based Access (Important):** To restrict Swagger access to specific roles, modify the `antMatchers` like this:
```java
.antMatchers("/v3/api-docs/**", "/swagger-ui/**", "/swagger-ui.html").hasRole("ADMIN") // Only ADMINs can see Swagger
```
This example restricts access to Swagger documentation to users with the `ADMIN` role. You can use any role you define in your application.
2. OpenAPI Customization (For Fine-Grained Control):
You can further customize the OpenAPI (Swagger) specification to hide or modify parts of the documentation based on roles. This is useful if you want to expose some endpoints to certain roles but not others, even within the Swagger UI.
*OpenAPI Customizer:** Use a `OpenApiCustomizer` bean to modify the `OpenAPI` object.
```java
@Configuration
public class OpenAPIConfig {
@Bean
public OpenApiCustomizer customizer() {
return openApi -> {
// Example: Remove certain paths based on role (you'll need to inject a SecurityContext or similar to get the user's roles)
if (!hasRole("ADMIN")) { // hasRole is a helper method to check user's roles
openApi.getPaths().remove("/admin-only-endpoint");
}
// Example: Modify operations based on role
openApi.getPaths().forEach((path, pathItem) -> {
pathItem.getGet().getParameters().add(new Parameter().name("api-key").in(ParameterIn.HEADER).description("API Key (if required)").required(false));
// Add security definitions if needed
openApi.getComponents().addSecuritySchemes("ApiKeyAuth", new SecurityScheme().type(SecurityScheme.Type.APIKEY).in(SecurityScheme.In.HEADER).name("X-API-KEY"));
});
};
}
//Helper method to get user Roles.
private boolean hasRole(String roleName){
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if(authentication != null && authentication.getAuthorities().stream().anyMatch(a -> a.getAuthority().equals("ROLE_"+roleName))){
return true;
}
return false;
}
}
```
3. API Key Authentication (Alternative or Complementary):
You could use API keys in addition to or instead of role-based authentication for Swagger. This is useful if you want to provide access to some APIs without requiring full user authentication.
*Add API Key Parameter:** Add an API key parameter to your OpenAPI specification (as shown in the `OpenApiCustomizer` example above).
*Interceptor/Filter:** Create an interceptor or filter that checks for the presence and validity of the API key in the request headers.
Key Considerations:
*Principle of Least Privilege:** Only expose the API endpoints and documentation that are absolutely necessary for each role.
*Testing:** Thoroughly test your security configuration to ensure that access is restricted correctly.
*SecurityContext:** In your `OpenApiCustomizer`, you'll need access to the `SecurityContext` to get the currently authenticated user and their roles. Inject `SecurityContextHolder` or a similar mechanism.
*Helper Methods:** Create helper methods (like the `hasRole` example) to simplify checking user roles in your customizer.
By implementing these measures, you can effectively secure your Swagger documentation and prevent unauthorized access to your API. Remember to choose the approach that best suits your needs and security requirements. Combining role-based access with API key authentication often provides the strongest security.
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