Springboot 防止XSS攻击，包含解决RequestBody 的Json 格式参数

本博文分为两部分

1.基于 表单key-value 传参方式防止XSS攻击

Content-Type	传参方式	接收方式
application/x-www-form-urlencoded	表单key-value	HttpServletRequest Parameters 获取
multipart/form-data	表单key-value	HttpServletRequest Parameters 获取

2.基于 json 传参方式防止XSS攻击

Content-Type	传参方式	接收方式
application/json	json格式文本	HttpServletRequest IO流获取

一：什么是XSS

XSS攻击全称跨站脚本攻击，是一种在web应用中的计算机安全漏洞，它允许恶意web用户将代码植入到提供给其它用户使用的页面中。

你可以自己做个简单尝试： 
1. 在任何一个表单内，你输入一段简单的js代码：<script>for(var i=0;i<1000;i++){alert("弹死你"+i);}</script>，将其存入数据库； 
2. 在页面上一个div元素内直接展示第一步内存入的值，你会发现弹出框出现了；

以上两个示例仅仅算是恶作剧，恶意用户能做的更多，如获取用户信息，进行“网络钓鱼”攻击等。

应对XSS攻击的其中一个方式就是后端对输入内容进行过滤，输入内容里面的敏感信息直接过滤，如<script>标签等。

 

==========基于 表单key-value 传参方式防止XSS攻击==========

本部分博文摘录转载至：https://www.cnblogs.com/mrBeany/p/10649853.html

二：添加Jsoup依赖

Jsoup使用标签白名单的机制用来进行防止XSS攻击, 假设白名单中只允许p标签存在, 此时在一段HTML代码中, 只能存在p标签 , 其他标签将会被清除只保留被标签所包裹的内容，当然，Jsoup不仅仅可以用来过滤，还可以用来爬虫，这里先不做说明，后期会单写一篇文章进行讲解。

<dependency>
   <groupId>org.jsoup</groupId>
   <artifactId>jsoup</artifactId>
   <version>1.10.2</version>
</dependency>

三：创建过滤器

在core下创建filter文件夹

1、创建过滤规则

package com.example.demo.core.filter;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.safety.Whitelist;

/**
 * @Description: xss非法标签过滤
 */
public class XssFilterUtil {

    /**
     * 使用自带的basicWithImages 白名单
     * 允许的便签有a,b,blockquote,br,cite,code,dd,dl,dt,em,i,li,ol,p,pre,q,small,span,
     * strike,strong,sub,sup,u,ul,img
     * 以及a标签的href,img标签的src,align,alt,height,width,title属性
     */
    private static final Whitelist whitelist = Whitelist.basicWithImages();

    /** 配置过滤化参数,不对代码进行格式化 */
    private static final Document.OutputSettings outputSettings = new Document.OutputSettings().prettyPrint(false);
    static {
        // 富文本编辑时一些样式是使用style来进行实现的
        // 比如红色字体 style="color:red;"
        // 所以需要给所有标签添加style属性
        whitelist.addAttributes(":all", "style");
    }

    public static String clean(String content) {
        return Jsoup.clean(content, "", whitelist, outputSettings);
    }
}

2、重写请求参数处理函数，这是实现XSS过滤的关键，在其内重写了getParameter，getParameterValues，getHeader等方法，对http请求内的参数进行了过滤。

package com.example.demo.core.filter;

import org.apache.commons.lang3.StringUtils;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

/**
 * 重写请求参数处理函数
 */
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
    HttpServletRequest orgRequest = null;

    private boolean isIncludeRichText = false;

    public XssHttpServletRequestWrapper(HttpServletRequest request, boolean isIncludeRichText) {
        super(request);
        orgRequest = request;
        this.isIncludeRichText = isIncludeRichText;
    }

    /**
     * 覆盖getParameter方法，将参数名和参数值都做xss过滤.
     * 如果需要获得原始的值，则通过super.getParameterValues(name)来获取
     * getParameterNames,getParameterValues和getParameterMap也可能需要覆盖
     */
    @Override
    public String getParameter(String name) {
        if (("content".equals(name) || name.endsWith("WithHtml")) && !isIncludeRichText) {
            return super.getParameter(name);
        }
        name = XssFilterUtil.clean(name);
        String value = super.getParameter(name);
        if (StringUtils.isNotBlank(value)) {
            value = XssFilterUtil.clean(value);
        }
        return value;
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] arr = super.getParameterValues(name);
        if (arr != null) {
            for (int i = 0; i < arr.length; i++) {
                arr[i] = XssFilterUtil.clean(arr[i]);
            }
        }
        return arr;
    }


    /**
     * 覆盖getHeader方法，将参数名和参数值都做xss过滤。<br/>
     * 如果需要获得原始的值，则通过super.getHeaders(name)来获取<br/>
     * getHeaderNames 也可能需要覆盖
     */
    @Override
    public String getHeader(String name) {
        name = XssFilterUtil.clean(name);
        String value = super.getHeader(name);
        if (StringUtils.isNotBlank(value)) {
            value = XssFilterUtil.clean(value);
        }
        return value;
    }

    /**
     * 获取最原始的request
     *
     * @return
     */
    public HttpServletRequest getOrgRequest() {
        return orgRequest;
    }

    /**
     * 获取最原始的request的静态方法
     *
     * @return
     */
    public static HttpServletRequest getOrgRequest(HttpServletRequest req) {
        if (req instanceof XssHttpServletRequestWrapper) {
            return ((XssHttpServletRequestWrapper) req).getOrgRequest();
        }
        return req;
    }

}

3、添加过滤XSS请求的入口，在这里通过XssHttpServletRequestWrapper将HttpServletRequest进行了封装，filterChain.doFilter(xssRequest, response);保证了后续代码执行request.getParameter，request.getParameterValues，request.getHeader时调用的都是XssHttpServletRequestWrapper内重写的方法，获取到的参数是已经进行过标签过滤的内容，从而消除了敏感信息。

package com.example.demo.core.filter;


import org.apache.commons.lang3.BooleanUtils;
import org.apache.commons.lang3.StringUtils;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @Description: 拦截防止xss注入 通过Jsoup过滤请求参数内的特定字符
 */
public class XssFilter implements Filter {

    //是否过滤富文本内容
    private static boolean IS_INCLUDE_RICH_TEXT = true;

    public List<String> excludes = new ArrayList<>();

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        if (handleExcludeURL(req, resp)) {
            filterChain.doFilter(request, response);
            return;
        }
        XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request, IS_INCLUDE_RICH_TEXT);
        filterChain.doFilter(xssRequest, response);
    }

    private boolean handleExcludeURL(HttpServletRequest request, HttpServletResponse response) {
        if (excludes == null || excludes.isEmpty()) {
            return false;
        }
        String url = request.getServletPath();
        for (String pattern : excludes) {
            Pattern p = Pattern.compile("^" + pattern);
            Matcher m = p.matcher(url);
            if (m.find()) {
                return true;
            }
        }
        return false;
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        String isIncludeRichText = filterConfig.getInitParameter("isIncludeRichText");
        if (StringUtils.isNotBlank(isIncludeRichText)) {
            IS_INCLUDE_RICH_TEXT = BooleanUtils.toBoolean(isIncludeRichText);
        }
        String temp = filterConfig.getInitParameter("excludes");
        if (temp != null) {
            String[] url = temp.split(",");
            for (int i = 0; url != null && i < url.length; i++) {
                excludes.add(url[i]);
            }
        }
    }

    @Override
    public void destroy() {
    }

}

四：注册过滤器

创建core→configurer→XssFilterConfigurer

package com.example.demo.core.configurer;

import com.example.demo.core.filter.XssFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashMap;
import java.util.Map;

/**
 * @Description:xss过滤拦截器配置文件
 */
@Configuration
public class XssFilterConfigurer {

    /**
     * xss过滤拦截器
     */
    @Bean
    public FilterRegistrationBean xssFilterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new XssFilter());
        filterRegistrationBean.setOrder(Integer.MAX_VALUE-1);
        filterRegistrationBean.setEnabled(true);
        filterRegistrationBean.addUrlPatterns("/*");
        Map<String, String> initParameters = new HashMap();
        //excludes用于配置不需要参数过滤的请求url
        initParameters.put("excludes", "/favicon.ico,/img/*,/js/*,/css/*");
        //isIncludeRichText主要用于设置富文本内容是否需要过滤
        initParameters.put("isIncludeRichText", "true");
        filterRegistrationBean.setInitParameters(initParameters);
        return filterRegistrationBean;
    }
}

 

==========基于 json 传参方式防止XSS攻击==========

本部分博文摘录转载至：https://blog.youkuaiyun.com/qq_36521507/article/details/105770952

 

重写extendMessageConverters，此方法注释说就是让来修改已经配置好的转化器列表呢，我们只需要遍历列表，找到MappingJackson2HttpMessageConverter，我们可以根据类型来判断哪个是 MappingJackson2HttpMessageConverter ，然后移除（注意遍历移除一定要用迭代器），把自定义的添加进去就好了，我们写在 WebMvcConfig 里

注：后台方法接收参数，需要以@RequestBody Object object （对象）形式 ， @RequestBody String json 此格式无效

package cn.sits.rjb.config.xss;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import org.apache.commons.lang3.StringEscapeUtils;
import org.codehaus.jackson.JsonProcessingException;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;

@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("swagger-ui.html")
                .addResourceLocations("classpath:/META-INF/resources/");

        registry.addResourceHandler("/webjars/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/");
    }


    @Override
    protected void extendMessageConverters(List<HttpMessageConverter<?>> messageConverters) {
        /**
         * 替换默认的MappingJackson2HttpMessageConverter，过滤(json请求参数)xss
         */
        ListIterator<HttpMessageConverter<?>> listIterator = messageConverters.listIterator();
        while(listIterator.hasNext()) {
            HttpMessageConverter<?> next = listIterator.next();
            if(next instanceof MappingJackson2HttpMessageConverter) {
                listIterator.remove();
                break;
            }
        }
        messageConverters.add(getMappingJackson2HttpMessageConverter());

    }

    public MappingJackson2HttpMessageConverter getMappingJackson2HttpMessageConverter() {
        // 创建自定义ObjectMapper
        SimpleModule module = new SimpleModule();
        module.addDeserializer(String.class, new JsonHtmlXssDeserializer(String.class));
        ObjectMapper objectMapper = Jackson2ObjectMapperBuilder.json().applicationContext(this.getApplicationContext()).build();
        objectMapper.registerModule(module);
        // 创建自定义消息转换器
        MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
        mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
        //设置中文编码格式
        List<MediaType> list = new ArrayList<>();
        list.add(MediaType.APPLICATION_JSON_UTF8);
        mappingJackson2HttpMessageConverter.setSupportedMediaTypes(list);
        return mappingJackson2HttpMessageConverter;
    }

}

/**
 * 对入参的json进行转义
 */
class JsonHtmlXssDeserializer extends JsonDeserializer<String> {

    public JsonHtmlXssDeserializer(Class<String> string) {
        super();
    }

    @Override
    public Class<String> handledType() {
        return String.class;
    }

    @Override
    public String deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException, JsonProcessingException {
        String value = jsonParser.getValueAsString();
        if (value != null) {
            return StringEscapeUtils.escapeHtml4(value.toString());
        }
        return value;
    }
}