XSS攻击简单来讲就是攻击者在请求中巧妙地加上执行脚本,达到攻击的目的。实践过滤器方案和JSP的EL表达式+JSTL标签库方案都还可以达到防XSS攻击的目的。
一.过滤器方案
XSSFilter.java
package com.bijian.study.filter; 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; /** * Servlet Filter implementation class XSSFilter */ @WebFilter("/XSSFilter") public class XSSFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void destroy() { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(new XSSRequestWrapper((HttpServletRequest) request), response); } }
XSSRequestWrapper.java
package com.bijian.study.filter; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import org.apache.commons.lang.StringEscapeUtils; public class XSSRequestWrapper extends HttpServletRequestWrapper { public XSSRequestWrapper(HttpServletRequest servletRequest) { super(servletRequest); } @Override public String[] getParameterValues(String parameter) { String[] values = super.getParameterValues(parameter); if (values == null) { return null; } int count = values.length; String[] encodedValues = new String[count]; for (int i = 0; i < count; i++) { encodedValues[i] = stripXSS(values[i]); } return encodedValues; } @Override public String getParameter(String parameter) { String value = super.getParameter(parameter); return stripXSS(value); } @Override public String getHeader(String name) { String value = super.getHeader(name); return stripXSS(value); } private String stripXSS(String value) { value = StringEscapeUtils.escapeHtml(value); value = StringEscapeUtils.escapeJavaScript(value); value = StringEscapeUtils.escapeSql(value); return value; } }
web.xml中的配置
<filter> <filter-name>XSSFilter</filter-name> <filter-class>com.bijian.study.filter.XSSFilter</filter-class> </filter> <filter-mapping> <filter-name>XSSFilter</filter-name> <url-pattern>*.do</url-pattern> </filter-mapping> <filter-mapping> <filter-name>XSSFilter</filter-name> <url-pattern>*.jsp</url-pattern> </filter-mapping>
二.JSP的EL表达式+JSTL标签库方案
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/"; String nameStr = request.getParameter("name");//用request得到 request.setAttribute("nameAttr", nameStr); %> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Hello</title> </head> <body> Hi,<c:out value="${nameAttr}"/> <!-- Hi,<%=nameStr%> Hi,${param.name} --> </body> </html>
XSS更详细的背景及方案,请参看:http://www.cnblogs.com/flyingeagle/articles/6746732.html