Citrix Metaframe Presentation Server bypassing policies

gustavog_at_grupoitpro.com.ar
Date: 09/30/05

  • Next message: Trustix Security Advisor: "TSLSA-2005-0053 - unzip" 
    Date: Fri, 30 Sep 2005 14:58:53 -0300 (ART)
To: bugtraq@securityfocus.com, vuln-dev@securityfocus.com, pen-test@securityfocus.com

    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

  • Next message: Trustix Security Advisor: "TSLSA-2005-0053 - unzip"

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