Description of Problem
The ICA protocol offers configurable encryption capabilities, known as SecureICA and ICA Basic encryption, that can be used to secure traffic between the ICA client and the server. These encryption capabilities are distinct from SSL/TLS encryption.
Under some circumstances, a vulnerability in Citrix Presentation Server could allow a client to establish a connection with encryption settings that are lower than the minimum configured by the administrator.
This does not affect the use of SSL/TLS by Citrix Presentation Server, or any other Citrix components.
This vulnerability affects the following products:
• Citrix Presentation Server versions up to and including 4.5 when installed on Windows 2003 Server.
• Citrix Access Essentials versions up to and including 2.0
• Citrix Desktop Server 1.0
Customers using other means of securing traffic between Citrix Presentation Server and its clients are not affected by this vulnerability. Such methods include Citrix SSL Relay, Citrix Secure Gateway, Citrix Access Gateway Standard, Advanced or Enterprise Edition
As best practice, Citrix already recommends the use of additional security technologies to their deployments due to limitations in SecureICA and Citrix Basic encryption. This is documented in articles CTX101737 and CTX155541.
What Customers Should Do
A hotfix has been released to address this issue. Citrix recommends that customers affected by this issue install the hotfix, which can be downloaded from the locations listed below.
Citrix Presentation Server 4.5 for Windows Server 2003:
Citrix Presentation Server 4.5 for Windows Server 2003 x64 Editions:
Citrix Presentation Server 4.0 for Windows Server 2003:
Citrix Access Essentials 2.0:
Citrix Access Essentials 1.5:
Citrix Access Essentials 1.0:
Citrix Desktop Server 1.0 for Windows Server 2003:
What Citrix Is Doing
Citrix is notifying customers and channel partners about this potential security issue. This article is also available from the Citrix Knowledge Base at http://support.citrix.com/.
Obtaining Support on this Issue
If you require technical assistance with this issue, please contact Citrix Technical Support. Information for contacting Citrix Technical Support is available at http://www.citrix.com/English/ss/supportContacts.asp.
Reporting Security Vulnerabilities to Citrix
Citrix welcomes input regarding the security of its products and considers any and all potential vulnerabilities seriously. If you would like to report a security issue to Citrix, please compose an e-mail to email@example.com containing the exact version of the product in which the vulnerability was found and the steps needed to reproduce the vulnerability.