Spring Boot利用filter实现xss防御

1.什么是xss？

• 来自用户的 UGC 信息
• 来自第三方的链接
• URL 参数
• POST 参数
• Referer （可能来自不可信的来源）
• Cookie （可能来自其他子域注入）

XSS 分类

• 存储区：恶意代码存放的位置。
• 插入点：由谁取得恶意代码，并插入到网页上。

存储型 XSS

1. 攻击者将恶意代码提交到目标网站的数据库中。
2. 用户打开目标网站时，网站服务端将恶意代码从数据库取出，拼接在 HTML 中返回给浏览器。
3. 用户浏览器接收到响应后解析执行，混在其中的恶意代码也被执行。
4. 恶意代码窃取用户数据并发送到攻击者的网站，或者冒充用户的行为，调用目标网站接口执行攻击者指定的操作。

反射型 XSS

1. 攻击者构造出特殊的 URL，其中包含恶意代码。
2. 用户打开带有恶意代码的 URL 时，网站服务端将恶意代码从 URL 中取出，拼接在 HTML 中返回给浏览器。
3. 用户浏览器接收到响应后解析执行，混在其中的恶意代码也被执行。
4. 恶意代码窃取用户数据并发送到攻击者的网站，或者冒充用户的行为，调用目标网站接口执行攻击者指定的操作。

DOM 型 XSS

1. 攻击者构造出特殊的 URL，其中包含恶意代码。
2. 用户打开带有恶意代码的 URL。
3. 用户浏览器接收到响应后解析执行，前端 JavaScript 取出 URL 中的恶意代码并执行。
4. 恶意代码窃取用户数据并发送到攻击者的网站，或者冒充用户的行为，调用目标网站接口执行攻击者指定的操作。

XSS 攻击的预防

1. 攻击者提交恶意代码。
2. 浏览器执行恶意代码。

• 输入过滤
• 预防存储型和反射型 XSS 攻击
• 纯前端渲染
• 转义 HTML
• 预防 DOM 型 XSS 攻击

2.代码工程

实验目标

利用过滤器实现xss拦截

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springboot-demo</artifactId>
        <groupId>com.et</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>xss</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>
        <dependency>
            <groupId>org.jsoup</groupId>
            <artifactId>jsoup</artifactId>
            <version>1.11.3</version>
        </dependency>
    </dependencies>
</project>

controller

package com.et.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

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

@RestController
public class HelloWorldController {
    @RequestMapping("/hello")
    public Map<String, Object> showHelloWorld(){
        Map<String, Object> map = new HashMap<>();
        map.put("msg", "HelloWorld");
        return map;
    }
    @RequestMapping("/api/xss")
    public void xssApiTest(String name, String content) {
        System.out.println("api->name:"+name);
        System.out.println("api->content:"+content);
    }
    /**
     * bu
     * @param name
     * @param content
     */
    @RequestMapping("/ui/xss")
    public void xssUiTest(String name, String content) {
        System.out.println("ui->name:"+name);
        System.out.println("ui->content:"+content);
    }
}

filter

package com.et.filter;


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;

/**
 * 
 * @author Frank
 *
 */
public class XssFilter implements Filter {
    /**
     * excludes  link
     */
   List<String> excludes = new ArrayList<String>();
    /**
     * xss filter switch
     */
    public boolean enabled = false;
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        String tempExcludes = filterConfig.getInitParameter("excludes");
        String tempEnabled = filterConfig.getInitParameter("enabled");
        if (StringUtils.isNotEmpty(tempExcludes)) {
            String[] url = tempExcludes.split(",");
            for (int i = 0; url != null && i < url.length; i++) {
                excludes.add(url[i]);
            }
        }
        if (StringUtils.isNotEmpty(tempEnabled)) {
            enabled = Boolean.valueOf(tempEnabled);
        }
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        if (handleExcludeURL(req, resp)) {
            chain.doFilter(request, response);
            return;
        }
        XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
        chain.doFilter(xssRequest, response);
    }
    private boolean handleExcludeURL(HttpServletRequest request, HttpServletResponse response) {
        if (!enabled) {
            return true;
        }
        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 destroy() {
    }
}

package com.et.filter;

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

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

/**
 * XSS filter process
 * 
 * @author Frank
 *
 */
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
    public XssHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }
    @Override
    public String[] getParameterValues(String name) {
        // Customize rules based on actual needs. Here, the content field is rich text and does not need to be filtered.
        if ("content".equals(name)) {
            return super.getParameterValues(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++) {
                // Prevent xss attacks and filter leading and trailing spaces
                escapseValues[i] = Jsoup.clean(values[i], Whitelist.relaxed()).trim();
            }
            return escapseValues;
        }
        return super.getParameterValues(name);
    }
}

config

package com.et.config;

import com.et.filter.XssFilter;
import org.springframework.beans.factory.annotation.Value;
import javax.servlet.DispatcherType;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.StringUtils;

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

/**
 * Filter config
 * @author Frank
 *
 */
@Configuration
public class FilterConfig
{
    @Value("${xss.enabled}")
    private String enabled;
    @Value("${xss.excludes}")
    private String excludes;
    @Value("${xss.urlPatterns}")
    private String urlPatterns;
    @SuppressWarnings({ "rawtypes", "unchecked" })
    @Bean
    public FilterRegistrationBean xssFilterRegistration()
    {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setDispatcherTypes(DispatcherType.REQUEST);
        registration.setFilter(new XssFilter());
        registration.addUrlPatterns(StringUtils.split(urlPatterns, ","));
        registration.setName("xssFilter");
        registration.setOrder(Integer.MAX_VALUE);
        Map<String, String> initParameters = new HashMap<String, String>();
        initParameters.put("excludes", excludes);
        initParameters.put("enabled", enabled);
        registration.setInitParameters(initParameters);
        return registration;
    }
}

application.yaml

server:
  port: 8088


xss:
  enabled: true
  #  Exclude links (separate multiple links with commas)
  excludes: /ui/*
  #  match links (separate multiple links with commas)
  urlPatterns: /api/*,/admin/*

代码仓库

• https://github.com/Harries/springboot-demo(xss)

3.测试

使用postman测试

4.引用

• https://tech.meituan.com/2018/09/27/fe-security.html
• http://www.liuhaihua.cn/archives/711462.html