===[ 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