Horde Framework and Horde IMP /index.php cross site referencing

scip AG Vulnerability ID 2456 (08/16/2006)
http://www.scip.ch/cgi-bin/smss/showadvf.pl?id=2456

I. INTRODUCTION

Horde is an open-source web application framework based on PHP. It
offers popular applications, such as the Horde IMP mail client, a
groupware and wiki solution.

More information is available on the official Horde product web site at
the following URL:

     http://www.horde.org/

II. DESCRIPTION

Marc Ruef found several web-based vulnerabilities that were identified
in Horde 3.0.4 and verified for all versions prior to 3.1.2 and IMP
prior to 4.1.3.

Horde is using a frameset to present the output to the user. The top
frame has the name horde_menu and the bottom frame has the name
horde_main. The main file index.php allows the definition of a source by
using the PHP variable $_GET['url']. An attacker might be able to do a
cross referencing and inserting malicous web site ressources.

This is very useful within technical supported phishing attacks. The
legitimate user might not be able to determine the real source of the
presentation. And therefore the attacker might be able to intercept the
communication and fetch some sensitive data.

III. EXPLOITATION

Classic script injection techniques within a browser session can be used
to exploit this vulnerabilities. [1, 2]

A plugin for our open-source exploiting framework "Attack Tool Kit"
(ATK) will be published in the near future. [3]

IV. IMPACT

Because non-authenticated parts of the software are affected too, this
vulnerabilities are serious for every secure environment.
Non-authenticated users might be able to exploit this flaw to gain
elevated privileges (e.g. extracting sensitive cookie information or
launch a buffer overflow attack against another web browser).

The other parts are affecting authenticated parts. This requires a
legitimate user to exploit the vulnerabilities. However, because cross
site scripting attacks could be launched from external attackers, these
vulnerabilities still become a high risk rating.

V. DETECTION

Detection of web based attacks requires a specialized web proxy and/or
intrusion detection system. Patterns for such a detection are available
and easy to implement.

VI. SOLUTION

The cross site scripting vulnerability (4) has been fixed in CVS HEAD
(Juli 2006) and FRAMEWORK_3. The other vulnerabilities were addressed in
the current release 3.1.2 and IMP 4.1.3.

VII. VENDOR RESPONSE

The Horde team has been informed at 07/04/2006 via email to
security-at-horde.org. A first response came back on the same day.
Several email messages were exchanged to discuss the vulnerabilities and
to co-ordinate the disclosure of this advisory.

VIII. SOURCES

scip AG - Security Consulting Information Process (german)
http://www.scip.ch

scip AG Vulnerability Database (german)
http://www.scip.ch/cgi-bin/smss/showadvf.pl?id=2456
http://www.scip.ch/cgi-bin/smss/showadvf.pl?id=2457

computec.ch document data base (german)
http://www.computec.ch/download.php

IX. DISCLOSURE TIMELINE

05/15/06 Identification of the vulnerabilities
07/04/06 Informing the Horde team
07/04/06 First reply of the Horde team
08/16/06 Public advisory

IX. CREDITS

The vulnerabilities were discovered by Marc Ruef.

     Marc Ruef, scip AG, Zuerich, Switzerland
     maru-at-scip.ch
     http://www.scip.ch

A1. BIBLIOGRAPHY

[1] http://www.computec.ch/download.php?view.812
[2] http://www.computec.ch/download.php?view.808
[3] http://www.computec.ch/projekte/atk/

A2. LEGAL NOTICES

Copyright (c) 2006 scip AG, Switzerland.

Permission is granted for the re-distribution of this alert. It may not
be edited in any way without permission of scip AG.

The information in the advisory is believed to be accurate at the time
of publishing based on currently available information. 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 from use of or reliance on this advisory.