JSP spring boot / cloud 使用filter防止XSS

2019-10-27 17:58:32

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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.

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