28. Security

If Spring Security is on the classpath then web applications will be secure by default with ‘basic’ authentication on all HTTP endpoints. To add method-level security to a web application you can also add @EnableGlobalMethodSecurity with your desired settings. Additional information can be found in the Spring Security Reference.

The default AuthenticationManager has a single user (‘user’ username and random password, printed at INFO level when the application starts up)

Using default security password: 78fa095d-3f4c-48b1-ad50-e24c31d5cf35
[Note]Note

If you fine-tune your logging configuration, ensure that the org.springframework.boot.autoconfigure.security category is set to log INFO messages, otherwise the default password will not be printed.

You can change the password by providing a security.user.password. This and other useful properties are externalized via SecurityProperties (properties prefix "security").

The default security configuration is implemented in SecurityAutoConfiguration and in the classes imported from there (SpringBootWebSecurityConfiguration for web security and AuthenticationManagerConfiguration for authentication configuration which is also relevant in non-web applications). To switch off the default web application security configuration completely you can add a bean with @EnableWebSecurity (this does not disable the authentication manager configuration or Actuator’s security). To customize it you normally use external properties and beans of type WebSecurityConfigurerAdapter (e.g. to add form-based login).

[Note]Note

If you add @EnableWebSecurity and also disable Actuator security, you will get the default form-based login for the entire application unless you add a custom WebSecurityConfigurerAdapter.

To also switch off the authentication manager configuration you can add a bean of type AuthenticationManager, or else configure the global AuthenticationManager by autowiring an AuthenticationManagerBuilder into a method in one of your @Configuration classes. There are several secure applications in the Spring Boot samples to get you started with common use cases.

The basic features you get out of the box in a web application are:

All of the above can be switched on and off or modified using external properties (security.*). To override the access rules without changing any other auto-configured features add a @Bean of type WebSecurityConfigurerAdapter with @Order(SecurityProperties.ACCESS_OVERRIDE_ORDER) and configure it to meet your needs.

[Note]Note

By default, a WebSecurityConfigurerAdapter will match any path. If you don’t want to completely override Spring Boot’s auto-configured access rules, your adapter must explicitly configure the paths that you do want to override.

28.1 OAuth2

If you have spring-security-oauth2 on your classpath you can take advantage of some auto-configuration to make it easy to set up Authorization or Resource Server. For full details, see the Spring Security OAuth 2 Developers Guide.

28.1.1 Authorization Server

To create an Authorization Server and grant access tokens you need to use @EnableAuthorizationServer and provide security.oauth2.client.client-id and security.oauth2.client.client-secret] properties. The client will be registered for you in an in-memory repository.

Having done that you will be able to use the client credentials to create an access token, for example:

$ curl client:[email protected]:8080/oauth/token -d grant_type=password -d username=user -d password=pwd

The basic auth credentials for the /token endpoint are the client-id and client-secret. The user credentials are the normal Spring Security user details (which default in Spring Boot to “user” and a random password).

To switch off the auto-configuration and configure the Authorization Server features yourself just add a @Bean of type AuthorizationServerConfigurer.

28.1.2 Resource Server

To use the access token you need a Resource Server (which can be the same as the Authorization Server). Creating a Resource Server is easy, just add @EnableResourceServer and provide some configuration to allow the server to decode access tokens. If your application is also an Authorization Server it already knows how to decode tokens, so there is nothing else to do. If your app is a standalone service then you need to give it some more configuration, one of the following options:

  • security.oauth2.resource.user-info-uri to use the /me resource (e.g. https://uaa.run.pivotal.io/userinfo on Pivotal Web Services (PWS))
  • security.oauth2.resource.token-info-uri to use the token decoding endpoint (e.g. https://uaa.run.pivotal.io/check_token on PWS).

If you specify both the user-info-uri and the token-info-uri then you can set a flag to say that one is preferred over the other (prefer-token-info=true is the default).

Alternatively (instead of user-info-uri or token-info-uri) if the tokens are JWTs you can configure a security.oauth2.resource.jwt.key-value to decode them locally (where the key is a verification key). The verification key value is either a symmetric secret or PEM-encoded RSA public key. If you don’t have the key and it’s public you can provide a URI where it can be downloaded (as a JSON object with a “value” field) with security.oauth2.resource.jwt.key-uri. E.g. on PWS:

$ curl https://uaa.run.pivotal.io/token_key
{"alg":"SHA256withRSA","value":"-----BEGIN PUBLIC KEY-----\nMIIBI...\n-----END PUBLIC KEY-----\n"}

Additionally, if your authorization server has an endpoint that returns a set of JSON Web Keys(JWKs), you can configure security.oauth2.resource.jwk.key-set-uri. E.g. on PWS:

$ curl https://uaa.run.pivotal.io/token_keys
{"keys":[{"kid":"key-1","alg":"RS256","value":"-----BEGIN PUBLIC KEY-----\nMIIBI...\n-----END PUBLIC KEY-----\n"]}
[Note]Note

Configuring both JWT and JWK properties will cause an error. Only one of security.oauth2.resource.jwt.key-uri (or security.oauth2.resource.jwt.key-value) and security.oauth2.resource.jwk.key-set-uri should be configured.

[Warning]Warning

If you use the security.oauth2.resource.jwt.key-uri or `security.oauth2.resource.jwk.key-set-uri, ` the authorization server needs to be running when your application starts up. It will log a warning if it can’t find the key, and tell you what to do to fix it.

OAuth2 resources are protected by a filter chain with order security.oauth2.resource.filter-order and the default is after the filter protecting the actuator endpoints by default (so actuator endpoints will stay on HTTP Basic unless you change the order).

28.2 Token Type in User Info

Google, and certain other 3rd party identity providers, are more strict about the token type name that is sent in the headers to the user info endpoint. The default is “Bearer” which suits most providers and matches the spec, but if you need to change it you can set security.oauth2.resource.token-type.

28.3 Customizing the User Info RestTemplate

If you have a user-info-uri, the resource server features use an OAuth2RestTemplate internally to fetch user details for authentication. This is provided as a @Bean of type UserInfoRestTemplateFactory. The default should be fine for most providers, but occasionally you might need to add additional interceptors, or change the request authenticator (which is how the token gets attached to outgoing requests). To add a customization just create a bean of type UserInfoRestTemplateCustomizer - it has a single method that will be called after the bean is created but before it is initialized. The rest template that is being customized here is only used internally to carry out authentication. Alternatively, you could define your own UserInfoRestTemplateFactory @Bean to take full control.

[Tip]Tip

To set an RSA key value in YAML use the “pipe” continuation marker to split it over multiple lines (“|”) and remember to indent the key value (it’s a standard YAML language feature). Example:

security:
    oauth2:
        resource:
            jwt:
                keyValue: |
                    -----BEGIN PUBLIC KEY-----
                    MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKC...
                    -----END PUBLIC KEY-----

28.3.1 Client

To make your web-app into an OAuth2 client you can simply add @EnableOAuth2Client and Spring Boot will create a OAuth2ClientContext and OAuth2ProtectedResourceDetails that are necessary to create an OAuth2RestOperations. Spring Boot does not automatically create such bean but you can easily create your own:

@Bean
public OAuth2RestTemplate oauth2RestTemplate(OAuth2ClientContext oauth2ClientContext,
        OAuth2ProtectedResourceDetails details) {
    return new OAuth2RestTemplate(details, oauth2ClientContext);
}
[Note]Note

You may want to add a qualifier and review your configuration as more than one RestTemplate may be defined in your application.

This configuration uses security.oauth2.client.* as credentials (the same as you might be using in the Authorization Server), but in addition it will need to know the authorization and token URIs in the Authorization Server. For example:

application.yml. 

security:
    oauth2:
        client:
            clientId: bd1c0a783ccdd1c9b9e4
            clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1
            accessTokenUri: https://github.com/login/oauth/access_token
            userAuthorizationUri: https://github.com/login/oauth/authorize
            clientAuthenticationScheme: form

An application with this configuration will redirect to Github for authorization when you attempt to use the OAuth2RestTemplate. If you are already signed into Github you won’t even notice that it has authenticated. These specific credentials will only work if your application is running on port 8080 (register your own client app in Github or other provider for more flexibility).

To limit the scope that the client asks for when it obtains an access token you can set security.oauth2.client.scope (comma separated or an array in YAML). By default the scope is empty and it is up to Authorization Server to decide what the defaults should be, usually depending on the settings in the client registration that it holds.

[Note]Note

There is also a setting for security.oauth2.client.client-authentication-scheme which defaults to “header” (but you might need to set it to “form” if, like Github for instance, your OAuth2 provider doesn’t like header authentication). In fact, the security.oauth2.client.* properties are bound to an instance of AuthorizationCodeResourceDetails so all its properties can be specified.

[Tip]Tip

In a non-web application you can still create an OAuth2RestOperations and it is still wired into the security.oauth2.client.* configuration. In this case it is a “client credentials token grant” you will be asking for if you use it (and there is no need to use @EnableOAuth2Client or @EnableOAuth2Sso). To prevent that infrastructure to be defined, just remove the security.oauth2.client.client-id from your configuration (or make it the empty string).

28.3.2 Single Sign On

An OAuth2 Client can be used to fetch user details from the provider (if such features are available) and then convert them into an Authentication token for Spring Security. The Resource Server above support this via the user-info-uri property This is the basis for a Single Sign On (SSO) protocol based on OAuth2, and Spring Boot makes it easy to participate by providing an annotation @EnableOAuth2Sso. The Github client above can protect all its resources and authenticate using the Github /user/ endpoint, by adding that annotation and declaring where to find the endpoint (in addition to the security.oauth2.client.* configuration already listed above):

application.yml. 

security:
    oauth2:
...
    resource:
        userInfoUri: https://api.github.com/user
        preferTokenInfo: false

Since all paths are secure by default, there is no “home” page that you can show to unauthenticated users and invite them to login (by visiting the /login path, or the path specified by security.oauth2.sso.login-path).

To customize the access rules or paths to protect, so you can add a “home” page for instance, @EnableOAuth2Sso can be added to a WebSecurityConfigurerAdapter and the annotation will cause it to be decorated and enhanced with the necessary pieces to get the /login path working. For example, here we simply allow unauthenticated access to the home page at "/" and keep the default for everything else:

@Configuration
static class WebSecurityConfiguration extends WebSecurityConfigurerAdapter {

    @Override
    public void init(WebSecurity web) {
        web.ignoring().antMatchers("/");
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.antMatcher("/**").authorizeRequests().anyRequest().authenticated();
    }

}

28.4 Actuator Security

If the Actuator is also in use, you will find:

  • The management endpoints are secure even if the application endpoints are insecure.
  • Security events are transformed into AuditEvent instances and published to the AuditEventRepository.
  • The default user will have the ACTUATOR role as well as the USER role.

The Actuator security features can be modified using external properties (management.security.*). To override the application access rules add a @Bean of type WebSecurityConfigurerAdapter and use @Order(SecurityProperties.ACCESS_OVERRIDE_ORDER) if you don’t want to override the actuator access rules, or @Order(ManagementServerProperties.ACCESS_OVERRIDE_ORDER) if you do want to override the actuator access rules.