Spring Security FAQ

Spring Security provides you with a flexible framework for your authentication and authorization requirements, but there are many other considerations for building a secure application that are outside its scope. Web applications are vulnerable to all kinds of attacks with which you should be familiar, preferably before you start development so that you can design and code with them in mind from the beginning. Check out the OWASP website for information on the major issues that face web application developers and the countermeasures you can use against them.

Suppose you are developing an enterprise application based on Spring. You typically need to address four security concerns : authentication, web request security, service layer security (your methods that implement business logic), and domain object instance security (different domain objects can have different permissions). With these typical requirements in mind, we have the following considerations:

For simple applications, servlet specification security may be enough. Although when considered within the context of web container portability, configuration requirements, limited web request security flexibility, and non-existent services layer and domain object instance security, it becomes clear why developers often look to alternative solutions.

Spring Security 3.0 and 3.1 require at least JDK 1.5 and also require Spring 3.0.3 as a minimum. Ideally, you should use the latest release versions to avoid problems.

Spring Security 2.0.x requires a minimum JDK version of 1.4 and is built against Spring 2.0.x. It should also be compatible with applications that use Spring 2.5.x.

This means that authentication has failed. It does not say why, as it is good practice to avoid giving details that might help an attacker guess account names or passwords.

This also means that, if you ask this question online, you should not expect an answer unless you provide additional information. As with any issue, you should check the output from the debug log and note any exception stacktraces and related messages. You should step through the code in a debugger to see where the authentication fails and why. You should also write a test case which exercises your authentication configuration outside the application. If you use hashed passwords, make sure the value stored in your database is exactly the same as the value produced by the PasswordEncoder configured in your application.

A common user problem with infinite loop and redirecting to the login page is caused by accidentally configuring the login page as a “secured” resource. Make sure your configuration allows anonymous access to the login page, either by excluding it from the security filter chain or marking it as requiring ROLE_ANONYMOUS.

If your AccessDecisionManager includes an AuthenticatedVoter, you can use the IS_AUTHENTICATED_ANONYMOUSLY attribute. This is automatically available if you use the standard namespace configuration setup.

From Spring Security 2.0.1 onwards, when you use namespace-based configuration, a check is made on loading the application context and a warning message logged if your login page appears to be protected.

This is a debug level message which occurs the first time an anonymous user attempts to access a protected resource.

It is normal and shouldn’t be anything to worry about.

The most common reason for this is that your browser has cached the page, and you are seeing a copy that is being retrieved from the browsers cache. Verify this by checking whether the browser is actually sending the request (check your server access logs and the debug log or use a suitable browser debugging plugin, such as “Tamper Data” for Firefox). This has nothing to do with Spring Security, and you should configure your application or server to set the appropriate Cache-Control response headers. Note that SSL requests are never cached.

The following listing shows another debug-level message that occurs the first time an anonymous user attempts to access a protected resource. However, this listing shows what happens when you do not have an AnonymousAuthenticationFilter in your filter chain configuration:

It is normal and is not something to worry about.

Note that the permissions for an LDAP directory often do not let you read the password for a user. Hence, it is often not possible to use the What is a UserDetailsService and do I need one? where Spring Security compares the stored password with the one submitted by the user. The most common approach is to use LDAP “bind”, which is one of the operations supported by the LDAP protocol. With this approach, Spring Security validates the password by trying to authenticate to the directory as the user.

The most common problem with LDAP authentication is a lack of knowledge of the directory server tree structure and configuration. This differs from one company to another, so you have to find it out yourself. Before adding a Spring Security LDAP configuration to an application, you should write a simple test by using standard Java LDAP code (without Spring Security involved) and make sure you can get that to work first. For example, to authenticate a user, you could use the following code:

Session management issues are a common source of questions. If you are developing Java web applications, you should understand how the session is maintained between the servlet container and the user’s browser. You should also understand the difference between secure and non-secure cookies and the implications of using HTTP and HTTPS and switching between the two. Spring Security has nothing to do with maintaining the session or providing session identifiers. This is entirely handled by the servlet container.

Browsers generally maintain a single session per browser instance. You cannot have two separate sessions at once. So if you log in again in another window or tab you are just reauthenticating in the same session. So, if you log in again in another window or tab, you are reauthenticating in the same session. The server does not know anything about tabs, windows, or browser instances. All it sees are HTTP requests, and it ties those to a particular session according to the value of the JSESSIONID cookie that they contain. When a user authenticates during a session, Spring Security’s concurrent session control checks the number of other authenticated sessions that they have. If they are already authenticated with the same session, re-authenticating has no effect.

With the default configuration, Spring Security changes the session ID when the user authenticates. If you use a Servlet 3.1 or newer container, the session ID is simply changed. If you use an older container, Spring Security invalidates the existing session, creates a new session, and transfers the session data to the new session. Changing the session identifier in this manner prevents “session-fixation” attacks. You can find more about this online and in the reference manual.

It doesn’t work - I just end up back at the login page after authenticating.

This happens because sessions created under HTTPS, for which the session cookie is marked as “secure”, cannot subsequently be used under HTTP. The browser does not send the cookie back to the server, and any session state (including the security context information) is lost. Starting a session in HTTP first should work, as the session cookie is not marked as secure. However, Spring Security’s Session Fixation Protection can interfere with this because it results in a new session ID cookie being sent back to the user’s browser, usually with the secure flag. To get around this, you can disable session fixation protection. However, in newer Servlet containers, you can also configure session cookies to never use the secure flag.

Sessions are maintained either by exchanging a session cookie or by adding a jsessionid parameter to URLs (this happens automatically if you use JSTL to output URLs or if you call HttpServletResponse.encodeUrl on URLs (before a redirect, for example). If clients have cookies disabled, and you are not rewriting URLs to include the jsessionid, the session is lost. Note that the use of cookies is preferred for security reasons, as it does not expose the session information in the URL.

Make sure you have added the listener to your web.xml file. It is essential to make sure that the Spring Security session registry is notified when a session is destroyed. Without it, the session information is not removed from the registry. The following example adds a listener in a web.xml file:

This usually means that the user’s application is creating a session somewhere but that they are not aware of it. The most common culprit is a JSP. Many people are not aware that JSPs create sessions by default. To prevent a JSP from creating a session, add the <%@ page session="false" %> directive to the top of the page.

If you have trouble working out where a session is being created, you can add some debugging code to track down the location(s). One way to do this is to add a javax.servlet.http.HttpSessionListener, which calls Thread.dumpStack() in the sessionCreated method, to your application.

If an HTTP 403 Forbidden error is returned for HTTP POST, but it works for HTTP GET, the issue is most likely related to CSRF. Either provide the CSRF Token or disable CSRF protection (the latter is not recommended).

By default, filters are not applied to forwards or includes. If you really want the security filters to be applied to forwards or includes, you have to configure these explicitly in your web.xml file by using the <dispatcher> element, which is a child element of the <filter-mapping> element.

In a Spring web application, the application context that holds the Spring MVC beans for the dispatcher servlet is often separate from the main application context. It is often defined in a file called myapp-servlet.xml, where myapp is the name assigned to the Spring DispatcherServlet in the web.xml file. An application can have multiple DispatcherServlet instances, each with its own isolated application context. The beans in these “child” contexts are not visible to the rest of the application. The “parent” application context is loaded by the ContextLoaderListener you define in your web.xml file and is visible to all the child contexts. This parent context is usually where you define your security configuration, including the <global-method-security> element. As a result, any security constraints applied to methods in these web beans are not enforced, since the beans cannot be seen from the DispatcherServlet context. You need to either move the <global-method-security> declaration to the web context or move the beans you want secured into the main application context.

Generally, we recommend applying method security at the service layer rather than on individual web controllers.

Why can’t I see the user information?

If you have excluded the request from the security filter chain by using the filters='none' attribute in the <intercept-url> element that matches the URL pattern, the SecurityContextHolder is not populated for that request. Check the debug log to see whether the request is passing through the filter chain. (You are reading the debug log, right?)

Method security does not hide links when using the url attribute in <sec:authorize>, because we cannot readily reverse engineer what URL is mapped to what controller endpoint. We are limited because controllers can rely on headers, the current user, and other details to determine what method to invoke.

The best way of locating classes is by installing the Spring Security source in your IDE. The distribution includes source jars for each of the modules the project is divided up into. Add these to your project source path, and then you can navigate directly to Spring Security classes (Ctrl-Shift-T in Eclipse). This also makes debugging easier and lets you troubleshoot exceptions by looking directly at the code where they occur to see what is going on there.

There is a general overview of what beans are created by the namespace in the namespace appendix of the reference guide. There is also a detailed blog article called "Behind the Spring Security Namespace" on blog.springsource.com. If you want to know the full details, then the code is in the spring-security-config module within the Spring Security 3.0 distribution. You should probably read the chapters on namespace parsing in the standard Spring Framework reference documentation first.

Spring Security has a voter-based architecture, which means that an access decision is made by a series of AccessDecisionVoter instances. The voters act on the “configuration attributes”, which are specified for a secured resource (such as a method invocation). With this approach, not all attributes may be relevant to all voters, and a voter needs to know when it should ignore an attribute (abstain) and when it should vote to grant or deny access based on the attribute value. The most common voter is the RoleVoter, which, by default, votes whenever it finds an attribute with the ROLE_ prefix. It makes a simple comparison of the attribute (such as ROLE_USER) with the names of the authorities that the current user has been assigned. If it finds a match (they have an authority called ROLE_USER), it votes to grant access. Otherwise, it votes to deny access.

You can change the prefix by setting the rolePrefix property of RoleVoter. If you need only to use roles in your application and have no need for other custom voters, you can set the prefix to a blank string. In that case, the RoleVoter treats all attributes as roles.

It depends on what features you are using and what type of application you are developing. With Spring Security 3.0, the project jars are divided into clearly distinct areas of functionality, so it is straightforward to work out which Spring Security jars you need from your application requirements. All applications need the spring-security-core jar. If you are developing a web application, you need the spring-security-web jar. If you are using security namespace configuration, you need the spring-security-config jar. For LDAP support, you need the spring-security-ldap jar. And so on.

For third-party jars, the situation is not always quite so obvious. A good starting point is to copy those from one of the pre-built sample applications WEB-INF/lib directories. For a basic application, you can start with the tutorial sample. For a basic application, you can start with the tutorial sample. If you want to use LDAP with an embedded test server, use the LDAP sample as a starting point. The reference manual also includes an appendix that lists the first-level dependencies for each Spring Security module, with some information on whether they are optional and when they are required.

If you build your project with Maven, adding the appropriate Spring Security modules as dependencies to your pom.xml file automatically pulls in the core jars that the framework requires. Any that are marked as “optional” in the Spring Security pom.xml files have to be added to your own pom.xml file if you need them.

If you use Maven, you need to add the following to your pom.xml file dependencies:

The other required jars should be pulled in transitively.

UserDetailsService is a DAO interface for loading data that is specific to a user account. It has no function other than to load that data for use by other components within the framework. It is not responsible for authenticating the user. Authenticating a user with a username and password combination is most commonly performed by the DaoAuthenticationProvider, which is injected with a UserDetailsService to let it load the password (and other data) for a user, to compare it with the submitted value. Note that, if you use LDAP, this approach may not work.

If you want to customize the authentication process, you should implement AuthenticationProvider yourself. See this blog article for an example that integrate Spring Security authentication with Google App Engine.

This question comes up repeatedly, so you can find more information by searching online.

The submitted login information is processed by an instance of UsernamePasswordAuthenticationFilter. You need to customize this class to handle the extra data fields. One option is to use your own customized authentication token class (rather than the standard UsernamePasswordAuthenticationToken). Another option is to concatenate the extra fields with the username (for example, by using a : character as the separator) and pass them in the username property of UsernamePasswordAuthenticationToken.

You also need to customize the actual authentication process. If you use a custom authentication token class, for example, you will have to write an AuthenticationProvider (or extend the standard DaoAuthenticationProvider) to handle it. If you have concatenated the fields, you can implement your own UserDetailsService to split them up and load the appropriate user data for authentication.

You cannot do this, since the fragment is not transmitted from the browser to the server. From the server’s perspective, the URLs are identical. This is a common question from GWT users.

You cannot (without resorting to something like thread-local variables), since the only information supplied to the interface is the username. Instead of implementing UserDetailsService, you should implement AuthenticationProvider directly and extract the information from the supplied Authentication token.

In a standard web setup, the getDetails() method on the Authentication object will return an instance of WebAuthenticationDetails. If you need additional information, you can inject a custom AuthenticationDetailsSource into the authentication filter you are using. If you are using the namespace, for example with the <form-login> element, then you should remove this element and replace it with a <custom-filter> declaration pointing to an explicitly configured UsernamePasswordAuthenticationFilter.

You cannot, since the UserDetailsService has no awareness of the servlet API. If you want to store custom user data, you should customize the UserDetails object that is returned. This can then be accessed at any point, through the thread-local SecurityContextHolder. A call to SecurityContextHolder.getContext().getAuthentication().getPrincipal() returns this custom object.

If you really need to access the session, you must do so by customizing the web tier.

You cannot (and should not, even if you find a way to do so). You are probably misunderstanding its purpose. See "What is a UserDetailsService?", earlier in the FAQ.

People often ask about how to store the mapping between secured URLs and security metadata attributes in a database rather than in the application context.

The first thing you should ask yourself is if you really need to do this. If an application needs to be secure, it also requires that the security be tested thoroughly based on a defined policy. It may require auditing and acceptance testing before being rolled out into a production environment. A security-conscious organization should be aware that the benefits of their diligent testing process could be wiped out instantly by letting the security settings be modified at runtime by changing a row or two in a configuration database. If you have taken this into account (perhaps by using multiple layers of security within your application), Spring Security lets you fully customize the source of security metadata. You can make it fully dynamic if you choose.

Both method and web security are protected by subclasses of AbstractSecurityInterceptor, which is configured with a SecurityMetadataSource from which it obtains the metadata for a particular method or filter invocation. For web security, the interceptor class is FilterSecurityInterceptor, and it uses the FilterInvocationSecurityMetadataSource marker interface. The “secured object” type it operates on is a FilterInvocation. The default implementation (which is used both in the namespace <http> and when configuring the interceptor explicitly) stores the list of URL patterns and their corresponding list of “configuration attributes” (instances of ConfigAttribute) in an in-memory map.

To load the data from an alternative source, you must use an explicitly declared security filter chain (typically Spring Security’s FilterChainProxy) to customize the FilterSecurityInterceptor bean. You cannot use the namespace. You would then implement FilterInvocationSecurityMetadataSource to load the data as you please for a particular FilterInvocation. The FilterInvocation object contains the HttpServletRequest, so you can obtain the URL or any other relevant information on which to base your decision, based on what the list of returned attributes contains. A basic outline would look something like the following example:

For more information, look at the code for DefaultFilterInvocationSecurityMetadataSource.

The LdapAuthenticationProvider bean (which handles normal LDAP authentication in Spring Security) is configured with two separate strategy interfaces, one that performs the authentication and one that loads the user authorities, called LdapAuthenticator and LdapAuthoritiesPopulator, respectively. The DefaultLdapAuthoritiesPopulator loads the user authorities from the LDAP directory and has various configuration parameters to let you specify how these should be retrieved.

To use JDBC instead, you can implement the interface yourself, by using whatever SQL is appropriate for your schema:

You would then add a bean of this type to your application context and inject it into the LdapAuthenticationProvider. This is covered in the section on configuring LDAP by using explicit Spring beans in the LDAP chapter of the reference manual. Note that you cannot use the namespace for configuration in this case. You should also consult the security-api-url[Javadoc] for the relevant classes and interfaces.

The namespace functionality is intentionally limited, so it does not cover everything that you can do with plain beans. If you want to do something simple, such as modifying a bean or injecting a different dependency, you can do so by adding a BeanPostProcessor to your configuration. You can find more information in the Spring Reference Manual. To do so, you need to know a bit about which beans are created, so you should also read the blog article mentioned in the earlier question on how the namespace maps to Spring beans.

Normally, you would add the functionality you require to the postProcessBeforeInitialization method of BeanPostProcessor. Suppose that you want to customize the AuthenticationDetailsSource used by the UsernamePasswordAuthenticationFilter (created by the form-login element). You want to extract a particular header called CUSTOM_HEADER from the request and use it while authenticating the user. The processor class would look like the following listing:

You would then register this bean in your application context. Spring automatically invoke it on the beans defined in the application context.