With the help of CSRF token we can sure incoming request is authenticated (know user not hacker)
Please note i have required below approach but google can't help me even on stackoverflow i did't get mentioned code below but after collection of stackoverflow answer i have made my day. So it's useful for further searching/ specially for beginners
I have described below Spring MVC with Spring Interceptor
Note - I have used google cache to store salt in cache for re verification
below dependency need to add pom.xml
<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>28.0-jre</version>
</dependency>
below HandlerInterceptorAdapter implemention
package com.august.security;
import java.security.SecureRandom;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.commons.lang3.RandomStringUtils;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
public class CsrfSecurity extends HandlerInterceptorAdapter {
List<String> urlList= new LinkedList<>();
private static final String CSRF_TAG = "CSRF-CHECK";
@SuppressWarnings("unchecked")
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handleer)
throws Exception {
System.out.println("Inside Pre Handler");
String reqUrl = request.getRequestURI().toString();
System.out.println("Request URL : " + reqUrl);
String ipAddress = request.getHeader("X-FORWARDED-FOR");
if (ipAddress == null) {
ipAddress = request.getRemoteAddr();
}
//local host url http://localhost:8080/august/
if (request.getRequestURI().contains("/august/")) {
System.out.println("pre handler return true");
//it will return and next executed postHandelr method
//because of on above url my webApplication page working
return true;
}
if (ignoreUrl().contains(request.getRequestURI())) {
System.out.println("inside ignore uri");
return true;
} else {
System.out.println("CSRF Security intercepter preHandle method started.......");
String salt = request.getParameter("csrfPreventionSalt");
HttpSession sessionAttribute = request.getSession();
Cache<String, Boolean> csrfPreventionSalt = (Cache<String, Boolean>) sessionAttribute
.getAttribute("csrfPreventionSalt");
if (csrfPreventionSalt == null) {
System.out.println("Salt not matched session expired..");
parameterValuesPrint(request, "saltCacheNotFound");
response.sendRedirect("error");
return false;
} else if (salt == null) {
parameterValuesPrint(request, "noSaltValue");
System.out.println("Potential CSRF detected !! inform ASAP");
response.sendRedirect("error");
return false;
} else if (csrfPreventionSalt.getIfPresent(salt) == null) {
System.out.println("saltValueMisMatch");
System.out.println("Potential CSRF detected !! inform ASAP");
response.sendRedirect("error");
} else {
request.setAttribute("csrfPreventionSalt", csrfPreventionSalt);
}
return true;
}
}
@SuppressWarnings("unchecked")
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) {
System.out.println("Inside post Handler");
System.out.println("CSRF Security key generator method started");
try {
//localhost url http://localhost:8080/august/
//api is my controller path so no need to genrate token for api
if (request.getRequestURI().contains("/august/api/")) {
System.out.println("No need to genrate salt for api");
} else {
HttpSession sessionAttribute = request.getSession();
Cache<String, Boolean> csrfPreventionSaltCache = (Cache<String, Boolean>) sessionAttribute
.getAttribute("csrfPreventionSalt");
System.out.println("csrfPreventionSaltCache ::: " + csrfPreventionSaltCache);
if (csrfPreventionSaltCache == null) {
csrfPreventionSaltCache = CacheBuilder.newBuilder().maximumSize(5000)
.expireAfterWrite(20, TimeUnit.MINUTES).build();
request.getSession().setAttribute("csrfPreventionSaltCache", csrfPreventionSaltCache);
}
String salt = RandomStringUtils.random(20, 0, 0, true, true, null, new SecureRandom());
System.out.println("csrfPreventionSalt genrated ::: " + salt);
csrfPreventionSaltCache.put(salt, Boolean.TRUE);
if (modelAndView != null) {
System.out.println("Model and view not null and salt is added in modelAndView");
modelAndView.addObject("csrfPreventionSalt", salt);
}
}
} catch (Exception ex) {
System.out.println(ex.getMessage());
ex.printStackTrace();
}
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("afterCompletion : ");
if (ex != null) {
System.out.println("exception : " + ex.getMessage());
ex.printStackTrace();
}
}
private List<String> ignoreUrl() {
if(urlList == null) {
urlList.add("/august/error");
//add here your ignored url.
}
return urlList;
}
private void parameterValuesPrint(HttpServletRequest request, String err) {
StringBuilder reqParamAndValue = new StringBuilder();
Enumeration<?> params = request.getParameterNames();
while (params.hasMoreElements()) {
Object objOri = params.nextElement();
String param = (String) objOri;
String value = request.getParameter(param);
reqParamAndValue = reqParamAndValue.append(param + "=" + value + ",");
}
System.out.println(CSRF_TAG + " " + err + "RequestedURL : " + request.getRequestURL());
}
}
Below is Interceptor registration with spring context
package com.august.configuration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.view.InternalResourceViewResolver;
import com.august.security.CsrfSecurity;
@Configuration
@EnableWebMvc
@ComponentScan(basePackages="com.august")
public class SpringConfiguration extends WebMvcConfigurerAdapter {
@Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
//viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/views/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
@Bean
public CsrfSecurity csrfSecurity() {
return new CsrfSecurity();
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new CsrfSecurity());
}
}
below is my controller
package com.august.v1.appcontroller;
import javax.servlet.http.HttpSession;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
@Controller
public class HomeController {
@Autowired
HttpSession httpSession;
@RequestMapping("/")
public String index(Model model) {
httpSession.invalidate();
System.out.println("Home page loaded");
return "index";
}
}
below is my index.jsp jsp page
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1" isELIgnored="false"%>
//don't forget to add isELIgnored="false" on old(version) jsp page because of i
//have wasted 1 hour for this
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>ADS Home</title>
</head>
<body>
<h1>${csrfPreventionSalt}</h1>
<input type="hidden" name="csrfPreventionSalt" value=${csrfPreventionSalt}>
</body>
</html>
For Understanding about CSRF - CSRF explanation
