servlet Filter is not allowing to load application resources - filter

Question

I am trying to prevent CSRF(Cross site request forgery). To prevent CSRF I have created filter which will filter every request.
After implementing the javax.servlet.Filter as expected filter does its job. But after implementing servlet filter my application resources are not loading properly.
CSS, jQuery, datatable, all the resources are not loading properly, some time they are loading, some time not.
Before implementing the filter it was working fine.
Sample error in firebug:
"NetworkError: 500 Internal Server Error - http://localhost:8080/myApp/resources/images/bg-report-content.jpg"
"NetworkError: 500 Internal Server Error - http://localhost:8080/myApp/resources/images/bg-header.jpg"
tworkError: 500 Internal Server Error - http://localhost:8080/myApp/resources/css/dataTables.bootstrap.css"
"NetworkError: 500 Internal Server Error - http://localhost:8080/myApp/resources/js/fnStandingRedraw.js"
"NetworkError: 500 Internal Server Error - http://localhost:8080/myApp/resources/js/dataTables.tableTools.js"
This How I implemented the Filter for CSRF
What I am doing is , I have created a class called LoadSalt whic creates the salt(random number). that random number I am taking in jsp. and along with the jsp I am sending it with the request.
LoadSalt calss
public class LoadSalt implements Filter{
public Cache<String, Boolean> csrfPreventionSaltCache= null;
HttpServletRequest httpReq=null;
//int count=0;
#SuppressWarnings("unchecked")
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
//count++;
// Assume its HTTP
httpReq = (HttpServletRequest)request;
if(httpReq.getAttribute("csrfPreventionSaltCache")!=null)
{
csrfPreventionSaltCache= (Cache<String, Boolean>) httpReq.getAttribute("csrfPreventionSaltCache");
}
if(csrfPreventionSaltCache == null)
{
// creating a new cache
csrfPreventionSaltCache = CacheBuilder.newBuilder().maximumSize(5000)
.expireAfterAccess(5, TimeUnit.MINUTES).build();
// Setting to httpReq
httpReq.setAttribute("csrfPreventionSaltCache", csrfPreventionSaltCache);
}
// Generate the salt and store it in the users cache
String salt = RandomStringUtils.random(20, 0, 0, true, true, null, new SecureRandom());
//System.out.println("Salt: "+salt);
csrfPreventionSaltCache.put(salt, Boolean.TRUE);
// Add the salt to the current request so it can be used
// by the page rendered in this request
httpReq.setAttribute("csrfPreventionSalt", salt);
chain.doFilter(httpReq, response);
}
public void init(FilterConfig arg0) throws ServletException {
}
public void destroy() {
}
}
The another filter which validate the salt
public class ValidateSalt implements Filter {
public Cache<String, Boolean> csrfPreventionSaltCache= null;
#SuppressWarnings("unchecked")
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// Assume its HTTP
HttpServletRequest httpReq = (HttpServletRequest) request;
HttpServletResponse httpResponse =(HttpServletResponse) response;
String salt =(String) httpReq.getAttribute("csrfPreventionSalt");
// Validate that the salt is in the cache
if(httpReq.getAttribute("csrfPreventionSaltCache")!=null)
{
csrfPreventionSaltCache = (Cache<String, Boolean>) httpReq.getAttribute("csrfPreventionSaltCache");
}
if(csrfPreventionSaltCache !=null && salt !=null && csrfPreventionSaltCache.getIfPresent(salt)!=null)
{
String metodName =httpReq.getMethod();
String saltFromJspPage = httpReq.getParameter("salt");
//String saltFromRequest =(String) httpReq.getAttribute("csrfPreventionSalt");
if(metodName.equalsIgnoreCase("POST"))
{
if(saltFromJspPage!=null && csrfPreventionSaltCache.getIfPresent(saltFromJspPage)!=null)
{
chain.doFilter(httpReq, response);
else
{
//throw new ServletException("Potential CSRF detected!! Please contact to system admin ASAP.");
httpResponse.sendRedirect("/myApp/pages/pageNotFound.jsp");
}
}
else
{
chain.doFilter(httpReq, response);
}
}
else
{
// Otherwise we throw an exception aborting the request flow
//throw new ServletException("Potential CSRF detected!! Inform a scary sysadmin ASAP.");
httpResponse.sendRedirect("/myApp/pages/pageNotFound.jsp");
}
}
public void init(FilterConfig arg0) throws ServletException {
}
public void destroy() {
}
}
servlet filter mapping in web.xml
<filter>
<filter-name>loadSalt</filter-name>
<filter-class>com.mpApp.security.LoadSalt</filter-class>
</filter>
<filter-mapping>
<filter-name>loadSalt</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>validateSalt</filter-name>
<filter-class>com.mpApp.security.ValidateSalt</filter-class>
</filter>
<filter-mapping>
<filter-name>validateSalt</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
What is wrong with my application?
Why servlet filter is not allowing to load resources?, though some time it does work , some time it does not,
What is the route cause of this?
Am I implementing servlet filter in wrong way.
please help.

Answer 1

The url pattern is too wide, will try to apply the salt to every request. Keep it to the dynamic parts you can set and check the salt value, like /transferOperationServlet or /prettyImportantServlet or *.jsp