xss--知识点

如何在springboot项目中进行XSS过滤

简单介绍

XSS : 跨站脚本攻击(Cross Site Scripting)，为不和层叠样式表(Cascading Style Sheets, CSS)的缩写混淆，故将跨站脚本攻击缩写为XSS。恶意攻击者往Web页面里插入恶意html代码，当用户浏览该页之时，嵌入其中Web里面的html代码会被执行，从而达到恶意攻击用户的特殊目的。
过滤方式:主要通过对html标签进行转义的方式达到过滤的目的

话不多说,直接上代码

实现方式,共分为三步:

第一步:在springboot启动类上添加@ServletComponentScan注解,该注解会自动扫描到我们自定义的filter(还有其他方式,这里就不赘述了,大家有兴趣的可以自行百度)

第二步:定义request的包装类,重写其中的关键方法

import com.alibaba.fastjson.JSON;
import org.apache.commons.text.StringEscapeUtils;
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.Map;
/**
 * ServletRequest包装类,对request做XSS过滤处理
 * @author Jozz
 */
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {

    public XssHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }

    @Override
    public String getHeader(String name) {
        return StringEscapeUtils.escapeHtml4(super.getHeader(name));
    }

    @Override
    public String getQueryString() {
        return StringEscapeUtils.escapeHtml4(super.getQueryString());
    }

    @Override
    public String getParameter(String name) {
        return StringEscapeUtils.escapeHtml4(super.getParameter(name));
    }

    @Override
    public String[] getParameterValues(String 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++){
                escapseValues[i] = StringEscapeUtils.escapeHtml4(values[i]);
            }
            return escapseValues;
        }
        return values;
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        String str=getRequestBody(super.getInputStream());
        Map<String,Object> map= JSON.parseObject(str,Map.class);
        Map<String,Object> resultMap=new HashMap<>(map.size());
        for(String key:map.keySet()){
            Object val=map.get(key);
            if(map.get(key) instanceof String){
                resultMap.put(key,StringEscapeUtils.escapeHtml4(val.toString()));
            }else{
                resultMap.put(key,val);
            }
        }
        str=JSON.toJSONString(resultMap);
        final ByteArrayInputStream bais = new ByteArrayInputStream(str.getBytes());
        return new ServletInputStream() {
            @Override
            public int read() throws IOException {
                return bais.read();
            }
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener listener) {
            }
        };
    }

    private String getRequestBody(InputStream stream) {
        String line = "";
        StringBuilder body = new StringBuilder();
        int counter = 0;

        // 读取POST提交的数据内容
        BufferedReader reader = new BufferedReader(new InputStreamReader(stream, Charset.forName("UTF-8")));
        try {
            while ((line = reader.readLine()) != null) {
                body.append(line);
                counter++;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return body.toString();
    }
}

其中的StringEscapeUtils来自:

    compile("org.apache.commons:commons-text:1.6")

第三步:自定义过滤器

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
/**
 * XSS过滤器
 * @author Jozz
 */
@WebFilter(filterName="xssFilter",urlPatterns="/*")
public class XssFilter implements Filter {

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

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)servletRequest;
        String path = request.getServletPath();
        //由于我的@WebFilter注解配置的是urlPatterns="/*"(过滤所有请求),所以这里对不需要过滤的静态资源url,作忽略处理(大家可以依照具体需求配置)
        String[] exclusionsUrls = {".js",".gif",".jpg",".png",".css",".ico"};
        for (String str : exclusionsUrls) {
            if (path.contains(str)) {
                filterChain.doFilter(servletRequest,servletResponse);
                return;
            }
        }
        filterChain.doFilter(new XssHttpServletRequestWrapper(request),servletResponse);
    }

    @Override
    public void destroy() {

    }
}