cPanel Cross Domain Scripting / Information Disclosure

`===[ Introduction ]===  
  
cPanel offers web hosting software that automates the intricate workings  
of web hosting servers.  
cPanel equips server administrators with the necessary tools to provide  
top-notch hosting to customers on tens of thousands of servers worldwide.  
  
  
===[ Description ]===  
  
I) Cross Domain Scripting :  
A local user can run JavaScript code in other user's domain and access  
cookies and compromise the victim website.  
POC : User "hacker" makes ".htmltemplates" directory in hacker's homepage  
(/home/hacker/.htmltemplates/) and makes "exploit" file containing  
JavaScript. Now this script can be called from hacker's domain  
(hacker.com) :  
http://hacker.com/cgi-sys/entropysearch.cgi?user=hacker&template=exploit  
  
But, the script is also accessible from other hosted domains (for example  
victim.com) :  
http://victim.com/cgi-sys/entropysearch.cgi?user=hacker&template=exploit  
  
Here, the hacker's code is running in another domain's area and  
victim.com's cookies can be read.  
A demonstrative video for this vulnerability can be found here :  
http://opensecurity.ca/media/cpanel-cross-domain-scripting.mp4  
  
II) Find existing system users :  
Any unauthorized visitor can find valid system users.  
POC : If the hacker calls "entropysearch.cgi" script with an invalid  
username, the error message will be :  
"Could not chdir into /.htmltemplates: No such file or directory"  
http://1.2.3.4/cgi-sys/entropysearch.cgi?user=notexist  
  
But if the hacker calls "entropysearch.cgi" script with a valid username,  
the error message will be :  
"Could not chdir into /home/victim/.htmltemplates: No such file or directory"  
http://1.2.3.4/cgi-sys/entropysearch.cgi?user=victim  
  
The hacker can make a dictionary attack to find several valid usernames.  
  
III) Find user's homepage :  
If a hacker knows the username, then user's homepage address can be found.  
POC :  
http://domain.com/cgi-sys/entropysearch.cgi?user=victim :  
"Could not chdir into /home2/victim/.htmltemplates: No such file or  
directory"  
  
This can be useful for further attacks.  
  
  
===[ Patching ]===  
  
cPanel believes that these are not security vulnerabilities, so the issue  
already exist.  
  
  
===[ Timeline ]===  
  
[06/12/2016] - Vendor notified  
[06/12/2016] - Vendor verified reception of the report  
[09/12/2016] - Vendor responded that these are not security vulnerabilities  
[10/12/2016] - POC video sent to vendor explaining the severity of cross  
domain scripting vulnerability  
[06/01/2017] - No response from vendor, so vendor was contacted again  
[11/01/2017] - No response from vendor, public disclosure  
  
  
===[ Credits ]===  
  
Vulnerabilities have been discovered by Omid @ Open Security.  
  
  
===[ References ]===  
  
Open Security :  
http://opensecurity.ca/  
  
Original Advisory :  
http://opensecurity.ca/2016/12/multiple-vulnerabilities-in-cpanel/  
  
POC Video :  
http://opensecurity.ca/media/cpanel-cross-domain-scripting.mp4  
  
`