JSP spring boot / cloud 使用filter防止XSS

JSP spring boot / cloud 使用filter防止XSS

一.前言

XSS(跨站脚本攻击)

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。

二.思路

基于filter拦截,将特殊字符替换为html转意字符 (如: "<" 转意为 "<") , 需要拦截的点如下:

• 请求头 requestHeader
• 请求体 requestBody
• 请求参数 requestParameter
  

三.实现

1.创建XssHttpServletRequestWrapper类

在获取请求头,请求参数的这些地方,将目标值使用HtmlUtils.htmlEscape方法转意为html字符,而避免恶意代码参与到后续的流程中

/**
* XssHttpServletRequestWrapper.java
* Created at 2016-09-19
* Created by wangkang
* Copyright (C) 2016 egridcloud.com, All rights reserved.
*/
package com.egridcloud.udf.core.xss;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import org.springframework.web.util.HtmlUtils;
/**
* 描述 : 跨站请求防范
*
* @author wangkang
*
*/
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
/**
* 描述 : 构造函数
*
* @param request 请求对象
*/
public XssHttpServletRequestWrapper(HttpServletRequest request) {
super(request);
}
@Override
public String getHeader(String name) {
String value = super.getHeader(name);
return HtmlUtils.htmlEscape(value);
}
@Override
public String getParameter(String name) {
String value = super.getParameter(name);
return HtmlUtils.htmlEscape(value);
}
@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] = HtmlUtils.htmlEscape(values[i]);
}
return escapseValues;
}
return super.getParameterValues(name);
}
}

2.创建XssStringJsonSerializer类

其次是涉及到json转换的地方,也一样需要进行转意,比如,rerquestBody,responseBody

/**
* XssStringJsonSerializer.java
* Created at 2016-09-19
* Created by wangkang
* Copyright (C) 2016 egridcloud.com, All rights reserved.
*/
package com.egridcloud.udf.core.xss;
import java.io.IOException;
import org.springframework.web.util.HtmlUtils;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
/**
* 描述 : 基于xss的JsonSerializer
*
* @author wangkang
*
*/
public class XssStringJsonSerializer extends JsonSerializer<String> {
@Override
public Class<String> handledType() {
return String.class;
}
@Override
public void serialize(String value, JsonGenerator jsonGenerator,
SerializerProvider serializerProvider) throws IOException {
if (value != null) {
String encodedValue = HtmlUtils.htmlEscape(value);
jsonGenerator.writeString(encodedValue);
}
}
}

3.创建Bean

在启动类中,创建XssObjectMapper的bean,替换spring boot原有的实例,用于整个系统的json转换.

/**
* 描述 : xssObjectMapper
*
* @param builder builder
* @return xssObjectMapper
*/
@Bean
@Primary
public ObjectMapper xssObjectMapper(Jackson2ObjectMapperBuilder builder) {
//解析器
ObjectMapper objectMapper = builder.createXmlMapper(false).build();
//注册xss解析器
SimpleModule xssModule = new SimpleModule("XssStringJsonSerializer");
xssModule.addSerializer(new XssStringJsonSerializer());
objectMapper.registerModule(xssModule);
//返回
return objectMapper;
}

4.创建XssFilter

首先是拦截所有的请求,然后在doFilter方法中,将HttpServletRequest强制类型转换成XssHttpServletRequestWrapper

然后传递下去.

/**
* XssFilter.java
* Created at 2016-09-19
* Created by wangkang
* Copyright (C) 2016 egridcloud.com, All rights reserved.
*/
package com.egridcloud.udf.core.xss;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 描述 : 跨站请求防范
*
* @author wangkang
*
*/
@WebFilter(filterName = "xssFilter", urlPatterns = "/*", asyncSupported = true)
public class XssFilter implements Filter {
/**
* 描述 : 日志
*/
private static final Logger LOGGER = LoggerFactory.getLogger(XssFilter.class);
@Override
public void init(FilterConfig filterConfig) throws ServletException {
LOGGER.debug("(XssFilter) initialize");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
XssHttpServletRequestWrapper xssRequest =
new XssHttpServletRequestWrapper((HttpServletRequest) request);
chain.doFilter(xssRequest, response);
}
@Override
public void destroy() {
LOGGER.debug("(XssFilter) destroy");
}
}

四.结束

本文虽基于spring boot实现主题,但是思路是一致的,不限于任何框架.

 感谢阅读，希望能帮助到大家，谢谢大家对本站的支持！

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