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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