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Horde Kronolith Arbitrary Local File Inclusion Vulnerability

11.29.06

BACKGROUND

Kronolith is a web-based calendar system written in PHP and utilizing the Horde Application Framework. It is generally installed along side Horde's IMP web mail product. More information can be obtained at the Kronolith site at http://www.horde.org/kronolith/

DESCRIPTION

Remote exploitation of a design error in Horde's Kronolith could allow an authenticated web mail user to execute arbitrary PHP code under the security context of the running Web server.

The vulnerability specifically exists due to a design error in the way it includes certain files. Specifically, the 'lib/FBView.php' file contains a function 'Kronolith_FreeBusy_View::factory' which will include local files that are supplied via the 'view' HTTP GET request parameter. An excerpt from the code follows:

 177 function &factory($view) 178 { 179 $driver = basename($view); 180 require_once dirname(__FILE__) . '/FBView/' . $view . '.php'; 

As you can see on line 179, input validation was done. However the resulting string was not used on line 180. Instead the unfiltered variable coming directly from the attacker is used. By utilizing directory traversal specifiers and null bytes, an attacker can trivially cause files stored on the Web server to be parsed as PHP code.

ANALYSIS

Successful exploitation could allow an attacker to include an arbitrary local file on the affected host. Due to the lack of input validation on $GET_['view'], directory traversal specifiers could be utilized to parse any file on the system as PHP code.

DETECTION

iDefense has confirmed that versions 2.0.1 through 2.1.3 of Horde Kronolith are vulnerable to this issue. Other versions are also likely to be vulnerable.

WORKAROUND

iDefense is unaware of any available workarounds for this vulnerability.

VENDOR RESPONSE

The Horde core team has addressed this vulnerability in versions 2.0.7 and 2.1.4 of Kronolith.

CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet.

DISCLOSURE TIMELINE

11/21/2006 Initial vendor notification
11/21/2006 Initial vendor response
11/29/2006 Coordinated public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2006 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.