Horde Kronolith Arbitrary Local File Inclusion Vulnerability

iDefense Security Advisory 11.27.06
http://labs.idefense.com/intelligence/vulnerabilities/
Nov 27, 2006

I. 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/

II. 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.

III. 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.

IV. 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.

V. WORKAROUND

iDefense is unaware of any available workarounds for this vulnerability.

VI. VENDOR RESPONSE

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

VII. CVE INFORMATION

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

VIII. DISCLOSURE TIMELINE

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

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, 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
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