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                             CERT-Renater

                 Note d'Information No. 2020/VULN632
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DATE                : 20/11/2020

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Citrix Hypervisor versions prior to
5.7.5.

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https://support.citrix.com/article/CTX285937
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CTX285937
Citrix Hypervisor Security Update
Security Bulletin | Medium | Created: 12 Nov 2020 | Modified: 12 Nov 2020

Applicable Products

    Citrix Hypervisor XenServer


Description of Problem

A security issue has been identified in Citrix Hypervisor that may allow
privileged code running in a guest VM to infer details of some
computations occurring in other VMs on the host.  This may, for example,
be used to infer a secret encryption key used by a web server in a
different VM.

A CVE identifier for this issue is not yet available.

CVE ID       Description        Vulnerability Type     Pre-conditions

TBA          Side-channel attack
             through exposed
             power-monitoring
             interface               CWE-1300        Malicious code
                                                    executing on the
                                                          host.


This issue affects all currently supported versions of Citrix Hypervisor
up to and including Citrix Hypervisor 8.2 LTSR.

In addition, Citrix is aware of two recently disclosed issues affecting
Intel CPUs which are addressed by updated microcode from Intel.
Although these are issues in the underlying hardware platform, Citrix
has included this updated microcode in the hotfixes associated with this
bulletin to assist customers who have not obtained updated firmware from
their hardware vendor.  These issues have the following identifiers:

    CVE-2020-8696
    CVE-2020-8698

These CPU issues may allow code running in a VM to obtain data being
used in computations within other VMs or other processes within the same
VM.

Customers should note that it is necessary to reboot the host for the
microcode update that protects against these Intel CPU issues to take
effect.  Customers who are using the Live Patching feature of Citrix
Hypervisor and who do not need the microcode update (either because they
are using a CPU from a different vendor or because they have already
updated their host BIOS/UEFI firmware) do not need to reboot the host
after applying the update.


What Customers Should Do

Citrix has released hotfixes to address this issue. Citrix recommends
that affected customers install these hotfixes as their patching
schedule allows.  The hotfixes can be downloaded from the following
locations:

Citrix Hypervisor 8.2 LTSR: CTX285172 –
https://support.citrix.com/article/CTX285172

Citrix Hypervisor 8.1: CTX285171 –
https://support.citrix.com/article/CTX285171

Citrix XenServer 7.1 LTSR CU2: CTX285170 –
https://support.citrix.com/article/CTX285170

Citrix XenServer 7.0: CTX285169 –
https://support.citrix.com/article/CTX285169

Customers who are using the Live Patching feature of Citrix Hypervisor
should consider rebooting the host machine if they are in need of the
microcode update described above.


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
Center at http://support.citrix.com/.


Obtaining Support on This Issue

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 details
on our vulnerability response process and guidance on how to report
security-related issues to Citrix, please visit the Citrix Trust Center
at https://www.citrix.com/about/trust-center/vulnerability-process.html.


Changelog

Date            Change
2020-11-12      Initial Publication


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+ CERT-RENATER       |    tel : 01-53-94-20-44          +
+ 23/25 Rue Daviel   |    fax : 01-53-94-20-41          +
+ 75013 Paris        |    email:cert@support.renater.fr +
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