Unusual php file in my all websites
I have a file called q.php that has appeared in all my websites hosted in the same server. Does anyone know what the file does?
I noticed this when I got an email from firstname.lastname@example.org.
The email says:
Dear Sir/Madam, CERT-In is tracking defacement of Indian websites on regular basis. We have found that the website "example.com" hosted on IP xxx.xxx.xxx.xxx has been defaced on 30.09.2016 by the hacker group "Aris Dot ID". The URL of the defaced website is: example.com//q.php
Content of q.php file:
I deleted the file from all my websites. But I am not sure what extra security should I implement for this.