6.22笔记（xss攻击的了解以及在springboot项目中的防护）

xss攻击

跨脚本攻击，攻击者会在web页面插入恶意的script代码，当用户访问的时候就会执行这个script代码达到攻击用户的目的

分为（解析恶意代码的几种情况）：

• 反射型：
  当用户点击xxs 攻击恶意链接时候，页面会跳转到 http://localhost:3001/xss 攻击者预先准备的页面，然后会返回攻击者准备的js脚本，该js脚本就在浏览器中执行了

• 存储型

  主要是将恶意代码上传或存储到服务器中，下次只要受害者浏览包含此恶意代码的页面就会执行恶意代码

• DOM-based

  持久性xss攻击

SpringBoot中的应用：

application.yml:

# 防止XSS攻击
xss:
  # 过滤开关
  enabled: false
  # 排除链接（多个用逗号分隔）
  excludes:
  # 匹配链接
  urlPatterns: /user/*

FilterConfig:

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import javax.servlet.DispatcherType;
import java.util.HashMap;
import java.util.Map;

/**
 * Filter配置
 *
 * @author xiaofei
 */
@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.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;
    }
}

XssFilter:

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;

/**
 * 防止XSS攻击的过滤器
 *
 * @author xiaofei
 */
public class XssFilter implements Filter {
    /**
     * 排除链接
     */
    public List<String> excludes = new ArrayList<>();

    /**
     * xss过滤开关
     */
    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() {

    }
}