JavaWeb XSS攻击防御

XSS概述

      跨站脚本攻击(Cross Site Scripting)，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。

实现Filter，实现XSS过滤器

package com.bj58.qf.filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * Created with IntelliJ IDEA.
 *
 * @author: zhubo
 * @description: 防止XSS注入攻击Filter过滤器
 * @time: 2018年05月02日
 * @modifytime:
 */
public class XSSFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
//对请求进行拦截,防xss处理
        chain.doFilter(new XSSRequestWrapper((HttpServletRequest) request),response);
    }

    @Override
    public void destroy() {

    }
}

继承HttpServletRequestWrapper，实现对请求参数的过滤

package com.bj58.qf.filter;

import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.regex.Pattern;

/**
 * Created with IntelliJ IDEA.
 *
 * @author: zhubo
 * @description:
 * @time: 2018年05月02日
 * @modifytime:
 */
public class XSSRequestWrapper extends HttpServletRequestWrapper {
    boolean isUpData = false;//判断是否是上传 上传忽略

    public XSSRequestWrapper(HttpServletRequest request) {
        super(request);
        String contentType = request.getContentType();
        if (null != contentType){
            isUpData =contentType.startsWith ("multipart");
        }
    }

    @Override
    public String getParameter(String name) {
        String value = super.getParameter(name);
        return stripXSS(value);
    }


    @Override
    public String[] getParameterValues(String name) {
        String[] values = super.getParameterValues(name);
        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;
    }

    /**
     * 获取request的属性时，做xss过滤
     */
    @Override
    public Object getAttribute(String name) {
        Object value = super.getAttribute(name);
        if (null != value && value instanceof String) {
            value = stripXSS((String) value);
        }
        return value;
    }

    @Override
    public String getHeader(String name) {
        String value = super.getHeader(name);
        return value;
    }

    private String stripXSS(String value) {
        if (value != null) {
            value = value.replaceAll(" ", "");

            // Avoid anything in a <script>alert(a);</script>" type of e­xpression
            Pattern scriptPattern = Pattern.compile("<script>(.*?)</script>", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // 删除单个的 </script> 标签
            scriptPattern = Pattern.compile("</script>", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // 删除单个的<script ...> 标签
            scriptPattern = Pattern.compile("<script(.*?)>",
                    Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");

            // Avoid eval(...) e­xpressions
            scriptPattern = Pattern.compile("eval\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid e­xpression(...) e­xpressions
            scriptPattern = Pattern.compile("e­xpression\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");

            // Avoid javascript:... e­xpressions
            scriptPattern = Pattern.compile("javascript:", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid vbscript:... e­xpressions
            scriptPattern = Pattern.compile("vbscript:", Pattern.CASE_INSENSITIVE);
            value = scriptPattern.matcher(value).replaceAll("");
            // Avoid onload= e­xpressions
            scriptPattern = Pattern.compile("onload(.*?)=", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
            value = scriptPattern.matcher(value).replaceAll("");
        }
        return value;
    }




    @Override
    public ServletInputStream getInputStream () throws IOException {
        if (isUpData){
            return super.getInputStream ();
        }else{

            final ByteArrayInputStream bais = new ByteArrayInputStream(inputHandlers(super.getInputStream()).getBytes(Charset.forName("UTF-8")));

            return new ServletInputStream() {

                @Override
                public int read() throws IOException {
                    return bais.read();
                }
            };
        }

    }
    public String inputHandlers(ServletInputStream servletInputStream){
        StringBuilder sb = new StringBuilder();
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new InputStreamReader(servletInputStream, Charset.forName("UTF-8")));
            String line = "";
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (servletInputStream != null) {
                try {
                    servletInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return  stripXSS(sb.toString());
    }
}

3、注入XSS过滤器，两种方式 
第一种方式：配置web.xml

<!-- xss过滤器 -->
<filter>
    <filter-name>XssSqlFilter</filter-name>
    <filter-class>cn.aric.xss.XssFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>XssSqlFilter</filter-name>
    <url-pattern>/*</url-pattern>
    <dispatcher>REQUEST</dispatcher>
    <dispatcher>FORWARD</dispatcher>
</filter-mapping>

第二种方式：注解

/**
 * 注入Xss过滤器(注解方式)
 */
public class WebInitializer implements WebApplicationInitializer{

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        //添加监听器
        servletContext.addListener(RequestContextListener.class);
        //添加过滤器
        Dynamic xssFilterRegistration = servletContext.addFilter("XssFilter", XssFilter.class);
        //添加映射规则
        xssFilterRegistration.addMappingForUrlPatterns(
                EnumSet.of(DispatcherType.REQUEST,DispatcherType.FORWARD,DispatcherType.INCLUDE), 
                false, 
                "/*");

    }

}