Citrix MetaFrame Presentation Server ClientName Policies Can Be Bypassed By Remote Authenticated Users
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SecurityTracker Alert ID: 1014994
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SecurityTracker URL: http://securitytracker.com/id?1014994
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CVE Reference: CVE-2005-3134
(Links to External Site)
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Updated: Jun 15 2008
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Original Entry Date: Sep 30 2005
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Impact: Host/resource access via network, User access via network
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Exploit Included: Yes
Vendor Confirmed: Yes
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Version(s): 3.0, 4.0
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Description: A vulnerability was reported in MetaFrame Presentation Server. A user can bypass ClientName server policies.
A user can edit the ClientName field in the 'launch.ica' file to bypass any Citrix policies that are based on the ClientName value.
The 'WI_[*]' value can be modified to exploit this flaw.
Gustavo Gurmandi of GrupoITPro Security Research Community discovered
this vulnerabiltily.
The original advisory is available at:
http://www.grupoitpro.com.ar/ctxpoliciesbypass.txt
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Impact: An authenticated user can bypass Citrix policies that are based on the ClientName value.
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Solution: No product solution was available at the time of this entry.
The vendor has issued a knowledge base article indicating that the
ClientName value should not be trusted, available at:
http://support.citrix.com/kb/entry!default.jspa?categoryID=275&externalID=CTX107705
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Vendor URL: support.citrix.com/kb/entry!default.jspa?categoryID=275&externalID=CTX107705 (Links to External Site)
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Cause: Authentication error
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Underlying OS: Windows (2000), Windows (2003)
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Reported By: gustavog@grupoitpro.com.ar
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Message History:
None.
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Source Message Contents
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Date: Fri, 30 Sep 2005 14:58:53 -0300 (ART)
From: gustavog@grupoitpro.com.ar
Subject: Citrix Metaframe Presentation Server bypassing policies
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DESCRIPTION:
============
Vulnerability in Presentation Server allow to user bypass citrix policy
which is applied to client name.
SOFTWARE: Citrix Metaframe Presentation Server 3.0 / 4.0
=========
INFO:
=====
Citrix Presentation Server policy is used for admins to restrict the user
environment
and these allow applying to: IP client, servers, Users, o Client Name.
When user used the Web Interface to access to application in citrix
environment
the CLIENT NAME used is WI_*, where (*) is a random value like
asdfserw34vc342dk
this extension allow admins to use citrix policy based in client name "WI_*"
This policy can be used to restrict "printing Mapping, Disk Mapping,
Control bandwidth, manage printer driver environment so..."
VULNERABILITY:
==============
When user uses the application in Web interface, he download and execute
automatic file "launch.ica"
If the user "save as" launch.ica in his pc, and edit with notepad
He can change the value in ClientName that another "WI_" and execute
When user connects to citrix with ica file modified to Presentation
Server, the value in clientname is different to the original one and
bypasses the citrix policies.
POC:
====
Here is an example extracted from launch.ica:
[Encoding]
InputEncoding=ISO8859_1
[WFClient]
Version=2
ClientName=WI_XXXX -> change this extension with other name to bypass the
citrix policies
TransportReconnectEnabled=On
RemoveICAFile=yes
ProxyType=None
ProxyTimeout=30000
VENDOR STATUS:
==============
http://support.citrix.com/kb/entry!default.jspa?categoryID=275&externalID=CTX107705
FIX:
====
No Hotfix released
CREDITS:
========
This vulnerability was discovered and researched by
Gustavo Gurmandi of GrupoITPro Security Research Community.
mail : gustavog@grupoiptro.com.ar
web : http://www.grupoitpro.com.ar
ORIGINAL ADVISORY:
==================
http://www.grupoitpro.com.ar/ctxpoliciesbypass.txt
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