Spring Security: Propagating Security Context to Spawned Threads

PROBLEM

Let’s assume we have the following Parent class…

@Service
class Parent {
    @Autowired
    Child child

    void run() {
        println "Parent: ${SecurityContextHolder.context.authentication?.principal}"

        child.run()

        println "Parent: Done"
    }
}

… and Child class…

@Service
class Child {
    @Async
    void run() {
        Thread.sleep(500)
        println "Child: ${SecurityContextHolder.context.authentication?.principal}"
    }
}

Let’s also assume the user has successfully logged in and Spring Security has set up the user authentication info.

The Parent will spawn a new thread (through @Async) to run Child.

When invoking the Parent, this is what we see:-

Parent: USER_PRINCIPAL
Parent: Done
Child: null

The Child, for some reason, doesn’t get the receive the user authentication info.

SOLUTION

By default, SecurityContextHolder uses MODE_THREADLOCAL to store the user authentication info. As a result, this info is not accessible to methods outside the current execution thread.

To fix this, configure SecurityContextHolder to use MODE_INHERITABLETHREADLOCAL to pass the user authentication info to other spawned threads.

@Configuration
@EnableAsync
class AppConfig {
    AppConfig() {
        SecurityContextHolder.setStrategyName(SecurityContextHolder.MODE_INHERITABLETHREADLOCAL)
    }
}

When invoking the Parent again, now the Child will also receive the user authentication object:-

Parent: USER_PRINCIPAL
Parent: Done
Child: USER_PRINCIPAL

JEE Security: Preventing Clickjacking Attacks

PROBLEM

Clickjacking is an attack that tricks the users to perform unintended actions… see OWASP’s Testing for Clickjacking (OTG-CLIENT-009)

SOLUTION

To prevent clickjacking attacks, the app must set X-FRAME-OPTIONS header with an appropriate value:-

  • DENY: this denies any domain using the page as an iFrame source. This is the best option.
  • SAMEORIGIN: this allows pages within the same domain to use other application pages as iFrame sources.
  • ALLOW-FROM [whitelisted domains]: this declares a list of domains that are allowed to include the pages as iFrame sources.

If set correctly, the HTTPS response should show X-FRAME-OPTIONS header:-

➜  ~ curl -i -k https://localhost:8443/
HTTP/1.1 200
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: 0
Strict-Transport-Security: max-age=31536000 ; includeSubDomains
X-Frame-Options: DENY
X-Application-Context: application:local:8443
Set-Cookie: JSESSIONID=04ADDAF886A20AA561021E869E980BCC; Path=/; Secure; HttpOnly
Content-Type: text/html;charset=UTF-8
Content-Language: en-US
Content-Length: 631
Date: Thu, 31 Aug 2017 14:56:57 GMT

There are several ways to set this header.

Solution 1: Using a servlet filter

You may create a servlet filter that sets X-FRAME-OPTIONS in the response header.

Here’s an example using web.xml-less Spring Boot:-

@SpringBootApplication
class Application extends SpringBootServletInitializer {
    static void main(String[] args) {
        SpringApplication.run(Application, args)
    }

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        return builder.sources(Application)
    }

    @Bean
    FilterRegistrationBean clickjackingPreventionFilter() {
        return new FilterRegistrationBean(
                urlPatterns: ['/**'],
                filter: new Filter() {
                    @Override
                    void init(final FilterConfig filterConfig) throws ServletException {
                    }

                    @Override
                    void doFilter(final ServletRequest servletRequest,
                                  final ServletResponse servletResponse,
                                  final FilterChain filterChain) throws IOException, ServletException {
                        final HttpServletResponse response = (HttpServletResponse) servletResponse
                        response.addHeader('X-FRAME-OPTIONS', 'DENY')
                        filterChain.doFilter(servletRequest, servletResponse)
                    }

                    @Override
                    void destroy() {
                    }
                }
        )
    }
}

Solution 2: Using Spring Security

Spring Security provides a very easy way to set the X-FRAME-OPTIONS header:-

@Configuration
@EnableWebSecurity
class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(final HttpSecurity http) throws Exception {
        http.
                headers().frameOptions().deny(). 
                and().
                authorizeRequests().
                antMatchers('/**').permitAll()
    }
}

Spring Security: Invalid CSRF Token ‘null’ was found on the request parameter ‘_csrf’ or header ‘X-CSRF-TOKEN’

PROBLEM

With Spring Security 4.x, the CSRF protection is enabled by default. You may disable it, but to be more aligned with OWASP and the industry security standard, it’s best to leave this setting the way it is. Learn more about CSRF attack…

To prevent this attack, Spring Security 4.x requires you to attach a server-side generated CSRF token on any POST, PUT or DELETE calls… basically, actions that may modify the request state. Their argument for not attaching this token on GET is to prevent this token value from leaking out.

Further, you will require to call POST /login and POST /logout now. In the past, you can call GET /j_spring_security_logout without problem.

If you invoke POST, PUT or DELETE without this CSRF token, you will get a 403 error with this message: "Invalid CSRF Token 'null' was found on the request parameter '_csrf' or header 'X-CSRF-TOKEN'.".

SOLUTION

To obtain this CSRF token, add this Spring Security custom tag to the JSP file:-

<!DOCTYPE html>
<html>
	<head>
	    <sec:csrfMetaTags/>
	</head>
	<body>
	</body>
</html>

The rendered HTML looks like this:-

<!DOCTYPE html>
<html class="no-js">
	<head>
	    <meta name="_csrf_parameter" content="_csrf" />
	    <meta name="_csrf_header" content="X-CSRF-TOKEN" />
	    <meta name="_csrf" content="e62835df-f1a0-49ea-bce7-bf96f998119c" />
	</head>
	<body>
	</body>
</html>

Finally, set the request header before making the AJAX call:-

var header = $("meta[name='_csrf_header']").attr("content");
var token = $("meta[name='_csrf']").attr("content");

$.ajax({
    url: '/test',
    type: 'POST',
    beforeSend: function(xhr){
        xhr.setRequestHeader(header, token);
    },
    success: function(data) {
        console.log(data);
    },
    error: function (xhr, ajaxOptions, thrownError) {
        console.log(xhr.status + ": " + thrownError);
    }
});

Spring Security: Forcing URLs to use HTTPS

PROBLEM

Your web application supports both HTTP and HTTPS. You want to force all URLs to use HTTPS.

SOLUTION

Spring Security has a simple configuration that allows us to redirect all HTTP-based URLs to HTTPS. All we have to do is to set requires-channel="https" on <security:intercept-url/> tag.

For example:-

<security:http auto-config="true">
	<security:form-login .../>
	<security:logout .../>
	
	<security:intercept-url pattern="/reports" access="ROLE_ADMIN" requires-channel="https"/>
	<security:intercept-url pattern="/login" access="IS_AUTHENTICATED_ANONYMOUSLY" requires-channel="https"/>
	<security:intercept-url pattern="/**" access="ROLE_USER" requires-channel="https"/>
</security:http>

With this configuration, when the user hits http://server/app, it will be redirected to https://server/app.

If we are seeing this “redirect loop” error…

… and the server log went bananas…

"GET /app HTTP/1.1" 302 0 
"GET /app/ HTTP/1.1" 302 0 
"GET /app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/app/app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/app/app/app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/app/app/app/app/app/ HTTP/1.1" 302 0 
"GET /app/app/app/app/app/app/app/app/app/ HTTP/1.1" 302 0 

… then, chances are we are not using the default HTTP port (80) and HTTPS port (443). To fix this, we have to specify the custom port mappings in the Spring Security configuration:-

<security:http auto-config="true">
	<security:form-login .../>
	<security:logout .../>
	
	<security:intercept-url pattern="/reports" access="ROLE_ADMIN" requires-channel="https"/>
	<security:intercept-url pattern="/login" access="IS_AUTHENTICATED_ANONYMOUSLY" requires-channel="https"/>
	<security:intercept-url pattern="/**" access="ROLE_USER" requires-channel="https"/>
	
	<security:port-mappings>
		<!-- Default ports -->
		<security:port-mapping http="80" https="443"/>
		<!-- Websphere default ports -->
		<security:port-mapping http="9080" https="9443"/>
		<!-- Tomcat default ports -->
		<security:port-mapping http="8080" https="8443"/>
		<!-- Jetty custom ports -->
		<security:port-mapping http="7777" https="7443"/>
	</security:port-mappings>
</security:http>

Now, when the user hits http://localhost:7777/app, it will be redirected to https://localhost:7443/app.

Spring Security: Handling 403 Error Page

If you are already using Spring, then you might want to use Spring Security to secure your web resources.

To do that, we specify the URI to be secured with <security:intercept-url/> tag:-

<beans ...>
    <!-- Error pages don't need to be secured -->
    <security:http pattern="/error/**" security="none"/>

    <security:http auto-config="true">
        <security:form-login ... />
        <security:logout ... />
        <security:intercept-url pattern="/top-secrets/**" access="ROLE_TOPSECRET"/>
    </security:http>
		
		...
</beans>

When users without role ROLE_TOPSECRET access /top-secrets/kfc-secret, they will see this default error page:-

This proves that Spring Security is doing its job. However, the default error page looks rather F.U.G.L.Y. Further, the error page may reveal too much information about the application server. The above error page shows the application runs on Jetty. If I’m a motherhacker, I would research all the possible vulnerabilities on this particular application server in attempt to hack it.

A better solution is to provide a friendly error page when the user access is denied. This can be done by specifying <security:access-denied-handler/> tag:-

<beans ...>
    <!-- Error pages don't need to be secured -->
    <security:http pattern="/error/**" security="none"/>

    <security:http auto-config="true">
        <security:form-login ... />
        <security:logout ... />
        <security:access-denied-handler error-page="/error/access-denied"/>
        <security:intercept-url pattern="/top-secrets/**" access="ROLE_TOPSECRET"/>
    </security:http>
		
		...
</beans>

Then, we create a simple error controller that returns the error page:-

@Controller
@RequestMapping(value = "/error")
public class ErrorController {
    @RequestMapping(value = "/access-denied", method = RequestMethod.GET)
    public String accessDenied() {
        return "error-access-denied";
    }
}

Now, the user will see this custom error page:-

This solution is better than the previous one. However, SiteMesh doesn’t have the opportunity to decorate this error page before it gets rendered.

To fix this, we can create a simple redirect to allow the request to make a full-round trip to the server so that SiteMesh can decorate the error page:-

@Controller
@RequestMapping(value = "/error")
public class ErrorController {
    @RequestMapping(value = "/router", method = RequestMethod.GET)
    public String errorRouter(@RequestParam("q") String resource) {
        return "redirect:/error/" + resource;
    }

    @RequestMapping(value = "/access-denied", method = RequestMethod.GET)
    public String accessDenied() {
        return "error-access-denied";
    }
}

Then, we tweak the Spring Security to use the error router URI:-

<beans ...>
    <!-- Error pages don't need to be secured -->
    <security:http pattern="/error/**" security="none"/>

    <security:http auto-config="true">
        <security:form-login ... />
        <security:logout ... />
        <security:access-denied-handler error-page="/error/router?q=access-denied"/>
        <security:intercept-url pattern="/top-secrets/**" access="ROLE_TOPSECRET"/>
    </security:http>
		
		...
</beans>

Now, the user will see this nice beautiful error page:-