J C Citrix Workspace app replaces and extends the full capabilities of Citrix Receiver. Citrix recommends using the latest version of Citrix Workspace app to access workspaces. You can also access workspaces using Internet Explorer 11, or the latest version of Edge, Chrome, Firefox, or Safari. You can find the updated Citrix security bulletin here. I won’t dive into too much detail on the named pipe that Citrix Workspace use to trigger software updates from the unprivileged Workspace app as details for this can be found within the original blog post. So, what did Citrix do to fix the previous vulnerability.

• Citrix Workspace App
• Receiver for Windows

Description of Problem

Click Here to Get the Latest Citrix Workspace App. Updated January 25, 2021. System Requirements for Citrix Workspace App here. Citrix Workspace app can be used on domain and non-domain joined PCs, tablets, and thin clients. Provides high performance use of virtualized Skype for Business, line of business and HDX 3D Pro engineering apps, multimedia, local app access.

A vulnerability has been identified in Citrix Workspace app and Receiver for Windows that could result in local drive access preferences not being enforced allowing an attacker read/write access to the clients local drives which could enable code execution on the client device.

This vulnerability has been assigned the following CVE number:

• CVE-2019-11634: Remote Code Execution Vulnerability in Citrix Workspace app for Windows prior to version 1904 and Receiver for Windows to LTSR 4.9 CU6 version earlier than 4.9.6001.

This vulnerability affects all versions of Citrix Workspace app for Windows and Receiver for Windows the fix is contained in Citrix Workspace app version 1904 or later and Receiver for Windows to LTSR 4.9 CU6 version 4.9.6001.

This vulnerability does not affect Citrix Workspace app and Receiver on any other platforms.

Mitigating Factors

Citrix strongly recommends that customers upgrade to the latest Citrix Workspace app for Windows and Receiver for Windows to address this vulnerability. In cases where the upgrade is not immediately possible applying a Client Selective Trust policy via GPO can be used to limit the exploitability of this vulnerability until the upgrade can be completed. The following settings must be set for both x86 and x64 hives and the client system must be rebooted to take effect.

Set all FileSecurityPermission to 0, which means No Access (See CTX133565 for further details)

And

Set InstantiatedSecurityPolicyEditabledefault to false (See CTX128792 for further details)

Note: Restarting Citrix Workspace app and Receiver is not sufficient to apply the changes, the operating system must be rebooted.

What Customers Should Do

A new version of Citrix Workspace app and Receiver for Windows has been released. Citrix strongly recommends that customers upgrade Citrix Workspace app to version 1904 or later and Receiver for Windows to LTSR 4.9 CU6 version 4.9.6001.

Ess driver. The new Citrix Workspace app version is available from the following Citrix website location:

The new LTSR version is available from the following Citrix website location:

Single Sign-on (SSO) could stop working, after applying the security update, for browsers other than Internet Explorer unless explicitly configured. Use the following documentation to ensure proper configuration post fix installation:

Acknowledgements

Citrix thanks Ollie Whitehouse, Richard Warren and Martin Hill of NCC Group for working with us to protect Citrix customers.

What Citrix Is Doing

Latest Citrix Workspace App Windows 10

Citrix is notifying customers and channel partners about this potential security issue. This article is also available from the Citrix Knowledge Center at http://support.citrix.com/.

Latest Citrix Workspace App Install

Obtaining Support on This Issue

Latest Citrix Workspace App Windows

If you require technical assistance with this issue, please contact Citrix Technical Support. Contact details for Citrix Technical Support are available at https://www.citrix.com/support/open-a-support-case.html.

Reporting Security Vulnerabilities

Citrix welcomes input regarding the security of its products and considers any and all potential vulnerabilities seriously. For guidance on how to report security-related issues to Citrix, please see the following document: CTX081743 – Reporting Security Issues to Citrix

Changelog