Banner Grabbing - Apache Server Version Disclousure

How it was found

Hello Nextcloud, I'd like to report a nice little bug.

Banner Grabbing is a technique used to gain information about a remote server. Additionally, this technique is use to get information about remote servers.

I've captured the HTTP request while visiting https://customerupdates.nextcloud.com and https://surveyserver.nextcloud.com

https://customerupdates.nextcloud.com/

GET / HTTP/1.1 Host: customerupdates.nextcloud.com User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:55.0) Gecko/20100101 Firefox/55.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8 Accept-Language: en-US Accept-Encoding: gzip, deflate, br Connection: keep-alive Upgrade-Insecure-Requests: 1 Cache-Control: max-age=0

HTTP/1.1 403 Forbidden Date: Tue, 19 Sep 2017 10:29:24 GMT Server: Apache/2.4.18 (Ubuntu) Strict-Transport-Security: max-age=15768000; includeSubDomains; preload Content-Length: 16 Content-Type: text/html; charset=iso-8859-1 Keep-Alive: timeout=5, max=100 Connection: Keep-Alive

Above you can see server version of Nextcloud [Apache/2.4.18 (Ubuntu)]

This information might help an attacker gain a greater understanding of the systems in use and potentially develop further attacks targeted at the specific version of Apache.

Impact An attacker might use the disclosed information to harvest specific security vulnerabilities for the version identified.

Remediation Configure your web server to prevent information leakage from the SERVER header of its HTTP response.

I hope you'll fix it!

I think and hope this report would impress you.

Let me know if u have any question Thanks Cheers Anas