JSP spring boot / cloud 使用filter防止XSS


            JSP spring boot / cloud 使用filter防止XSS

一.前言

XSS(跨站脚本攻击)

跨站脚本攻击(Cross Site Scripting)，为不和层叠样式表(Cascading Style Sheets, CSS)的缩写混淆，故将跨站脚本攻击缩写为XSS。恶意攻击者往Web页面里插入恶意Script代码，当用户浏览该页之时，嵌入其中Web里面的Script代码会被执行，从而达到恶意攻击用户的目的。

二.思路

基于filter拦截,将特殊字符替换为html转意字符 (如: "<" 转意为 "<") , 需要拦截的点如下:



  请求头 requestHeader

  请求体 requestBody

  请求参数 requestParameter

  



三.实现

1.创建XssHttpServletRequestWrapper类

在获取请求头,请求参数的这些地方,将目标值使用HtmlUtils.htmlEscape方法转意为html字符,而避免恶意代码参与到后续的流程中





/**

 * XssHttpServletRequestWrapper.java

 * Created at 2016-09-19

 * Created by wangkang

 * Copyright (C) 2016 egridcloud.com, All rights reserved.

 */

package com.egridcloud.udf.core.xss;



import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;



import org.springframework.web.util.HtmlUtils;



/**

 * 描述 : 跨站请求防范

 *

 * @author wangkang

 *

 */

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {



 /**

  * 描述 : 构造函数

  *

  * @param request 请求对象

  */

 public XssHttpServletRequestWrapper(HttpServletRequest request) {

  super(request);

 }



 @Override

 public String getHeader(String name) {

  String value = super.getHeader(name);

  return HtmlUtils.htmlEscape(value);

 }



 @Override

 public String getParameter(String name) {

  String value = super.getParameter(name);

  return HtmlUtils.htmlEscape(value);

 }



 @Override

 public String[] getParameterValues(String name) {

  String[] values = super.getParameterValues(name);

  if (values != null) {

   int length = values.length;

   String[] escapseValues = new String[length];

   for (int i = 0; i < length; i++) {

    escapseValues[i] = HtmlUtils.htmlEscape(values[i]);

   }

   return escapseValues;

  }

  return super.getParameterValues(name);

 }



}







2.创建XssStringJsonSerializer类

其次是涉及到json转换的地方,也一样需要进行转意,比如,rerquestBody,responseBody





/**

 * XssStringJsonSerializer.java

 * Created at 2016-09-19

 * Created by wangkang

 * Copyright (C) 2016 egridcloud.com, All rights reserved.

 */

package com.egridcloud.udf.core.xss;



import java.io.IOException;



import org.springframework.web.util.HtmlUtils;



import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.databind.JsonSerializer;

import com.fasterxml.jackson.databind.SerializerProvider;



/**

 * 描述 : 基于xss的JsonSerializer

 *

 * @author wangkang

 *

 */

public class XssStringJsonSerializer extends JsonSerializer<String> {



 @Override

 public Class<String> handledType() {

  return String.class;

 }



 @Override

 public void serialize(String value, JsonGenerator jsonGenerator,

   SerializerProvider serializerProvider) throws IOException {

  if (value != null) {

   String encodedValue = HtmlUtils.htmlEscape(value);

   jsonGenerator.writeString(encodedValue);

  }

 }



}







3.创建Bean

在启动类中,创建XssObjectMapper的bean,替换spring boot原有的实例,用于整个系统的json转换.





 /**

  * 描述 : xssObjectMapper

  *

  * @param builder builder

  * @return xssObjectMapper

  */

 @Bean

 @Primary

 public ObjectMapper xssObjectMapper(Jackson2ObjectMapperBuilder builder) {

  //解析器

  ObjectMapper objectMapper = builder.createXmlMapper(false).build();

  //注册xss解析器

  SimpleModule xssModule = new SimpleModule("XssStringJsonSerializer");

  xssModule.addSerializer(new XssStringJsonSerializer());

  objectMapper.registerModule(xssModule);

  //返回

  return objectMapper;

 }





4.创建XssFilter

首先是拦截所有的请求,然后在doFilter方法中,将HttpServletRequest强制类型转换成XssHttpServletRequestWrapper

然后传递下去.





/**

 * XssFilter.java

 * Created at 2016-09-19

 * Created by wangkang

 * Copyright (C) 2016 egridcloud.com, All rights reserved.

 */

package com.egridcloud.udf.core.xss;



import java.io.IOException;



import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.annotation.WebFilter;

import javax.servlet.http.HttpServletRequest;



import org.slf4j.Logger;

import org.slf4j.LoggerFactory;



/**

 * 描述 : 跨站请求防范

 *

 * @author wangkang

 *

 */

@WebFilter(filterName = "xssFilter", urlPatterns = "/*", asyncSupported = true)

public class XssFilter implements Filter {



 /**

  * 描述 : 日志

  */

 private static final Logger LOGGER = LoggerFactory.getLogger(XssFilter.class);



 @Override

 public void init(FilterConfig filterConfig) throws ServletException {

  LOGGER.debug("(XssFilter) initialize");

 }



 @Override

 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

   throws IOException, ServletException {

  XssHttpServletRequestWrapper xssRequest =

    new XssHttpServletRequestWrapper((HttpServletRequest) request);

  chain.doFilter(xssRequest, response);

 }



 @Override

 public void destroy() {

  LOGGER.debug("(XssFilter) destroy");

 }



}







四.结束

本文虽基于spring boot实现主题,但是思路是一致的,不限于任何框架.

 感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！