cPanel Cross Domain Scripting / Information Disclosure
Posted on 14 January 2017
===[ 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
