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&externalI D=CTX107705 FIX: ==== No Hotfix released CREDITS: ======== This vulnerability was discovered and researched by Gustavo Gurmandi of GrupoITPro Security Research Community. mail : gustavog (at) grupoiptro.com (dot) ar [email concealed] web : http://www.grupoitpro.com.ar ORIGINAL ADVISORY: ================== http://www.grupoitpro.com.ar/ctxpoliciesbypass.txt