Tikiwiki tiki-editpage Arbitrary File Exposure Vulnerability

iDEFENSE Security Advisory 11.10.05
www.idefense.com/application/poi/display?id=337&type=vulnerabilities
November 10, 2005

I. BACKGROUND

Tikiwiki Community Portal is a full featured, freely available,
Wiki/CMS/Groupware system written in PHP. More information is available
at:

    http://tikiwiki.org/

II. DESCRIPTION

Remote exploitation of an input validation vulnerability in Tikiwiki
allows attackers to gain access to arbitrary files on the vulnerable
system under the privileges of the underlying web-server.

The problem specifically exists in the following snippet of code from
tiki-editpage.php:

    $sdta = @file_get_contents($suck_url);
    ...
        $htmlparser = new HtmlParser($sdta, $grammar, '', 0);
        $htmlparser->Parse();

No sanity checking is done on the 'suck_url' parameter prior to
utilizing it as the path to a file to read and parse. By specifying a
path with directory traversal modifiers an attacker can request an
arbitrary file to load and render on the screen.

III. ANALYSIS

Successful exploitation allows unauthenticated remote attackers to
access arbitrary files on the vulnerable system with the privileges of
the underlying web-server. If external database access is allowed, then
exploitation can result in a full database compromise as the database
credentials are easily exposed through this vulnerability.

IV. DETECTION

iDEFENSE has confirmed the existence of this issue in Tikiwiki versions
1.8.4 and 1.8.5. It is suspected that earlier versions are vulnerable as
well.

V. WORKAROUND

Restrict unnecessary access to Tikiwiki with firewall filters or HTTP
based authentication. If remote database connectivity is not required,
configure the underlying database server to bind to localhost only or
firewall the listening port to accept trusted hosts only.

VI. VENDOR RESPONSE

This vulnerability has been addressed in Tikiwiki 1.9.1 which is
available for download at:

  http://tikiwiki.org/tiki-index.php?page=Download

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-1925 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

06/07/2005  Initial vendor notification
08/21/2005  Initial vendor response
11/10/2005  Public disclosure

IX. CREDIT

codeauditor@gmail.com is credited with this discovery.

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X. LEGAL NOTICES

Copyright C 2005 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
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written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
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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.