spring security中的csrf防御原理(跨域请求伪造)

什么是csrf？

csrf又称跨域请求伪造，攻击方通过伪造用户请求访问受信任站点。CSRF这种攻击方式在2000年已经被国外的安全人员提出，但在国内，直到06年才开始被关注，08年，国内外的多个大型社区和交互网站分别爆出CSRF漏洞，如：NYTimes.com（纽约时报）、Metafilter（一个大型的BLOG网站），YouTube和百度HI......而现在，互联网上的许多站点仍对此毫无防备，以至于安全业界称CSRF为“沉睡的巨人”。

举个例子，用户通过表单发送请求到银行网站，银行网站获取请求参数后对用户账户做出更改。在用户没有退出银行网站情况下，访问了攻击网站，攻击网站中有一段跨域访问的代码，可能自动触发也可能点击提交按钮，访问的url正是银行网站接受表单的url。因为都来自于用户的浏览器端，银行将请求看作是用户发起的，所以对请求进行了处理，造成的结果就是用户的银行账户被攻击网站修改。

解决方法基本上都是增加攻击网站无法获取到的一些表单信息，比如增加图片验证码，可以杜绝csrf攻击，但是除了登陆注册之外，其他的地方都不适合放验证码，因为降低了网站易用性

相关介绍：

http://baike.baidu.com/view/1609487.htm?fr=aladdin

spring-servlet中配置csrf

<!-- Spring csrf 拦截器 -->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/login" />
<bean class="com.wangzhixuan.commons.csrf.CsrfInterceptor" />
</mvc:interceptor>
</mvc:interceptors>

在类中声明Csrf拦截器，用来生成或去除CsrfToken

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import com.wangzhixuan.commons.scan.ExceptionResolver;
import com.wangzhixuan.commons.utils.WebUtils;

/**
* Csrf拦截器，用来生成或去除CsrfToken
*
* @author L.cm
*/
public class CsrfInterceptor extends HandlerInterceptorAdapter {
private static final Logger logger = LogManager.getLogger(ExceptionResolver.class);

@Autowired
private CsrfTokenRepository csrfTokenRepository;

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
HandlerMethod handlerMethod = (HandlerMethod) handler;
// 非控制器请求直接跳出
if (!(handler instanceof HandlerMethod)) {
return true;
}
CsrfToken csrfToken = handlerMethod.getMethodAnnotation(CsrfToken.class);
// 判断是否含有@CsrfToken注解
if (null == csrfToken) {
return true;
}
// create、remove同时为true时异常
if (csrfToken.create() && csrfToken.remove()) {
logger.error("CsrfToken attr create and remove can Not at the same time to true!");
return renderError(request, response, Boolean.FALSE, "CsrfToken attr create and remove can Not at the same time to true!");
}
// 创建
if (csrfToken.create()) {
CsrfTokenBean token = csrfTokenRepository.generateToken(request);
csrfTokenRepository.saveToken(token, request, response);
// 缓存一个表单页面地址的url
csrfTokenRepository.cacheUrl(request, response);
request.setAttribute(token.getParameterName(), token);
return true;
}
// 判断是否ajax请求
boolean isAjax = WebUtils.isAjax(handlerMethod);
// 校验，并且清除
CsrfTokenBean tokenBean = csrfTokenRepository.loadToken(request);
if (tokenBean == null) {
return renderError(request, response, isAjax, "CsrfToken is null!");
}
String actualToken = request.getHeader(tokenBean.getHeaderName());
if (actualToken == null) {
actualToken = request.getParameter(tokenBean.getParameterName());
}
if (!tokenBean.getToken().equals(actualToken)) {
return renderError(request, response, isAjax, "CsrfToken not eq!");
}
return true;
}

private boolean renderError(HttpServletRequest request, HttpServletResponse response,
boolean isAjax, String message) throws IOException {
// 获取缓存的cacheUrl
String cachedUrl = csrfTokenRepository.getRemoveCacheUrl(request, response);
// ajax请求直接抛出异常，因为{@link ExceptionResolver}会去处理
if (isAjax) {
throw new RuntimeException(message);
}
// 非ajax CsrfToken校验异常，先清理token
csrfTokenRepository.saveToken(null, request, response);
logger.info("Csrf[redirectUrl]:\t" + cachedUrl);
response.sendRedirect(cachedUrl);
return false;
}

/**
* 用于清理@CsrfToken保证只能请求成功一次
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
HandlerMethod handlerMethod = (HandlerMethod) handler;
// 非控制器请求直接跳出
if (!(handler instanceof HandlerMethod)) {
return;
}
CsrfToken csrfToken = handlerMethod.getMethodAnnotation(CsrfToken.class);
if (csrfToken == null || !csrfToken.remove()) {
return;
}
csrfTokenRepository.getRemoveCacheUrl(request, response);
csrfTokenRepository.saveToken(null, request, response);
}

}

声明Csrf过滤注解，通过标注来过滤对应的请求

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
* Csrf过滤注解
* @author L.cm
*/
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface CsrfToken {
boolean create() default false;
boolean remove() default false;
}

建立实例对象（操作对象）

import java.io.Serializable;
import org.springframework.util.Assert;
public class CsrfTokenBean implements Serializable {
private static final long serialVersionUID = -6865031901744243607L;
private final String token;
private final String parameterName;
private final String headerName;
/**
* Creates a new instance
* @param headerName the HTTP header name to use
* @param parameterName the HTTP parameter name to use
* @param token the value of the token (i.e. expected value of the HTTP parameter of
* parametername).
*/
public CsrfTokenBean(String headerName, String parameterName, String token) {
Assert.hasLength(headerName, "headerName cannot be null or empty");
Assert.hasLength(parameterName, "parameterName cannot be null or empty");
Assert.hasLength(token, "token cannot be null or empty");
this.headerName = headerName;
this.parameterName = parameterName;
this.token = token;
}
public String getHeaderName() {
return this.headerName;
}
public String getParameterName() {
return this.parameterName;
}
public String getToken() {
return this.token;
}
}

过滤过程中需要的仓库

package com.wangzhixuan.commons.csrf;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public interface CsrfTokenRepository {
/**
* Generates a {@link CsrfTokenBean}
*
* @param request the {@link HttpServletRequest} to use
* @return the {@link CsrfTokenBean} that was generated. Cannot be null.
*/
CsrfTokenBean generateToken(HttpServletRequest request);
/**
* Saves the {@link CsrfTokenBean} using the {@link HttpServletRequest} and
* {@link HttpServletResponse}. If the {@link CsrfTokenBean} is null, it is the same as
* deleting it.
*
* @param token the {@link CsrfTokenBean} to save or null to delete
* @param request the {@link HttpServletRequest} to use
* @param response the {@link HttpServletResponse} to use
*/
void saveToken(CsrfTokenBean token, HttpServletRequest request,
HttpServletResponse response);
/**
* Loads the expected {@link CsrfTokenBean} from the {@link HttpServletRequest}
*
* @param request the {@link HttpServletRequest} to use
* @return the {@link CsrfTokenBean} or null if none exists
*/
CsrfTokenBean loadToken(HttpServletRequest request);
/**
* 缓存来源的url
* @param request request the {@link HttpServletRequest} to use
* @param response the {@link HttpServletResponse} to use
*/
void cacheUrl(HttpServletRequest request, HttpServletResponse response);
/**
* 获取并清理来源的url
* @param request the {@link HttpServletRequest} to use
* @param response the {@link HttpServletResponse} to use
* @return 来源url
*/
String getRemoveCacheUrl(HttpServletRequest request, HttpServletResponse response);
}

HttpSessionCsrfTokenRepository

package com.wangzhixuan.commons.csrf;
import java.util.UUID;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.wangzhixuan.commons.utils.StringUtils;
public final class HttpSessionCsrfTokenRepository implements CsrfTokenRepository {
private static final String DEFAULT_CSRF_PARAMETER_NAME = "_csrf";
private static final String DEFAULT_CSRF_HEADER_NAME = "X-CSRF-TOKEN";
private static final String DEFAULT_CSRF_TOKEN_ATTR_NAME = HttpSessionCsrfTokenRepository.class
.getName().concat(".CSRF_TOKEN");
private static final String DEFAULT_CACHE_URL_ATTR_NAME = HttpSessionCsrfTokenRepository.class
.getName().concat(".CACHE_URL");
private String parameterName = DEFAULT_CSRF_PARAMETER_NAME;
private String headerName = DEFAULT_CSRF_HEADER_NAME;
private String sessionAttributeName = DEFAULT_CSRF_TOKEN_ATTR_NAME;
private String cacheUrlAttributeName = DEFAULT_CACHE_URL_ATTR_NAME;
/*
* (non-Javadoc)
*
* @see org.springframework.security.web.csrf.CsrfTokenRepository#saveToken(org.
* springframework .security.web.csrf.CsrfToken,
* javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public void saveToken(CsrfTokenBean token, HttpServletRequest request,
HttpServletResponse response) {
if (token == null) {
HttpSession session = request.getSession(false);
if (session != null) {
session.removeAttribute(this.sessionAttributeName);
}
}
else {
HttpSession session = request.getSession();
session.setAttribute(this.sessionAttributeName, token);
}
}
/*
* (non-Javadoc)
*
* @see
* org.springframework.security.web.csrf.CsrfTokenRepository#loadToken(javax.servlet
* .http.HttpServletRequest)
*/
public CsrfTokenBean loadToken(HttpServletRequest request) {
HttpSession session = request.getSession(false);
if (session == null) {
return null;
}
return (CsrfTokenBean) session.getAttribute(this.sessionAttributeName);
}
/*
* (non-Javadoc)
*
* @see org.springframework.security.web.csrf.CsrfTokenRepository#generateToken(javax.
* servlet .http.HttpServletRequest)
*/
public CsrfTokenBean generateToken(HttpServletRequest request) {
return new CsrfTokenBean(this.headerName, this.parameterName,
createNewToken());
}
private String createNewToken() {
return UUID.randomUUID().toString();
}
@Override
public void cacheUrl(HttpServletRequest request, HttpServletResponse response) {
String queryString = request.getQueryString();
// 被拦截前的请求URL
String redirectUrl = request.getRequestURI();
if (StringUtils.isNotBlank(queryString)) {
redirectUrl = redirectUrl.concat("?").concat(queryString);
}
HttpSession session = request.getSession();
session.setAttribute(this.cacheUrlAttributeName, redirectUrl);
}
@Override
public String getRemoveCacheUrl(HttpServletRequest request, HttpServletResponse response) {
HttpSession session = request.getSession(false);
if (session == null) {
return null;
}
String redirectUrl = (String) session.getAttribute(this.cacheUrlAttributeName);
if (StringUtils.isBlank(redirectUrl)) {
return null;
}
session.removeAttribute(this.cacheUrlAttributeName);
return redirectUrl;
}
}

总结

以上所述是小编给大家介绍的spring security中的csrf防御原理(跨域请求伪造)，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
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