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spring security中的csrf防禦原理(跨域請求偽造)

什麼是csrf?

csrf又稱跨域請求偽造,攻擊方通過偽造使用者請求訪問受信任站點。CSRF這種攻擊方式在2000年已經被國外的安全人員提出,但在國內,直到06年才開始被關注,08年,國內外的多個大型社群和互動網站分別爆出CSRF漏洞,如:NYTimes.com(紐約時報)、Metafilter(一個大型的BLOG網站),YouTube和百度HI......而現在,網際網路上的許多站點仍對此毫無防備,以至於安全業界稱CSRF為“沉睡的巨人”。

舉個例子,使用者通過表單傳送請求到銀行網站,銀行網站獲取請求引數後對使用者賬戶做出更改。在使用者沒有退出銀行網站情況下,訪問了攻擊網站,攻擊網站中有一段跨域訪問的程式碼,可能自動觸發也可能點選提交按鈕,訪問的url正是銀行網站接受表單的url。因為都來自於使用者的瀏覽器端,銀行將請求看作是使用者發起的,所以對請求進行了處理,造成的結果就是使用者的銀行賬戶被攻擊網站修改。

解決方法基本上都是增加攻擊網站無法獲取到的一些表單資訊,比如增加圖片驗證碼,可以杜絕csrf攻擊,但是除了登陸註冊之外,其他的地方都不適合放驗證碼,因為降低了網站易用性

相關介紹:

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

spring-servlet中配置csrf

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

在類中宣告Csrf攔截器,用來生成或去除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攔截器,用來生成或去除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;
  // 非控制器請求直接跳出
  if (!(handler instanceof HandlerMethod)) {
   return true;
  }
  CsrfToken csrfToken = handlerMethod.getMethodAnnotation(CsrfToken.class);
  // 判斷是否含有@CsrfToken註解
  if (null == csrfToken) {
   return true;
  }
  // create、remove同時為true時異常
  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!");
  }
  // 建立
  if (csrfToken.create()) {
   CsrfTokenBean token = csrfTokenRepository.generateToken(request);
   csrfTokenRepository.saveToken(token,request,response);
   // 快取一個表單頁面地址的url
   csrfTokenRepository.cacheUrl(request,response);
   request.setAttribute(token.getParameterName(),token);
   return true;
  }
  // 判斷是否ajax請求
  boolean isAjax = WebUtils.isAjax(handlerMethod);
  // 校驗,並且清除
  CsrfTokenBean tokenBean = csrfTokenRepository.loadToken(request);
  if (tokenBean == null) {
   return renderError(request,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,"CsrfToken not eq!");
  }
  return true;
 }
 
 private boolean renderError(HttpServletRequest request,boolean isAjax,String message) throws IOException {
  // 獲取快取的cacheUrl
  String cachedUrl = csrfTokenRepository.getRemoveCacheUrl(request,response);
  // ajax請求直接丟擲異常,因為{@link ExceptionResolver}會去處理
  if (isAjax) {
   throw new RuntimeException(message);
  }
  // 非ajax CsrfToken校驗異常,先清理token
  csrfTokenRepository.saveToken(null,response);
  logger.info("Csrf[redirectUrl]:\t" + cachedUrl);
  response.sendRedirect(cachedUrl);
  return false;
 }

 /**
  * 用於清理@CsrfToken保證只能請求成功一次
  */
 @Override
 public void postHandle(HttpServletRequest request,Object handler,ModelAndView modelAndView) throws Exception {
  HandlerMethod handlerMethod = (HandlerMethod) handler;
  // 非控制器請求直接跳出
  if (!(handler instanceof HandlerMethod)) {
   return;
  }
  CsrfToken csrfToken = handlerMethod.getMethodAnnotation(CsrfToken.class);
  if (csrfToken == null || !csrfToken.remove()) {
   return;
  }
  csrfTokenRepository.getRemoveCacheUrl(request,response);
  csrfTokenRepository.saveToken(null,response);
 }

}

宣告Csrf過濾註解,通過標註來過濾對應的請求

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

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

建立例項物件(操作物件)

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;
 }
}

過濾過程中需要的倉庫

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);
 /**
  * 快取來源的url
  * @param request request the {@link HttpServletRequest} to use
  * @param response the {@link HttpServletResponse} to use
  */
 void cacheUrl(HttpServletRequest request,HttpServletResponse response);
 /**
  * 獲取並清理來源的url
  * @param request the {@link HttpServletRequest} to use
  * @param response the {@link HttpServletResponse} to use
  * @return 來源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,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();
  // 被攔截前的請求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;
 }
}

總結

以上所述是小編給大家介紹的spring security中的csrf防禦原理(跨域請求偽造),希望對大家有所幫助,如果大家有任何疑問請給我留言,小編會及時回覆大家的。在此也非常感謝大家對我們網站的支援!
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