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             AUSCERT External Security Bulletin Redistribution

              Citrix XenServer gets multiple security updates
                                14 May 2018


        AusCERT Security Bulletin Summary

Product:           Citrix XenServer
Publisher:         Citrix
Operating System:  Linux variants
                   BSD variants
Impact/Access:     Increased Privileges   -- Existing Account   
                   Access Privileged Data -- Existing Account   
                   Denial of Service      -- Existing Account   
                   Reduced Security       -- Unknown/Unspecified
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-10982 CVE-2018-8897 CVE-2017-5754

Original Bulletin: 

Revision History:  May 14 2018: Source article added missing CVE identifier
                   May 10 2018: Initial Release

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Citrix XenServer Multiple Security Updates

Security Bulletin | High
Created: 08 May 2018 | Modified: 08 May 2018

Applicable Products

  * XenServer 6.0.2
  * XenServer 6.2.0
  * XenServer 6.5
  * XenServer 7.0
  * XenServer 7.1
  * XenServer 7.2
  * XenServer 7.3
  * XenServer 7.4

Description of Problem

A number of security vulnerabilities have been identified in Citrix XenServer
that may allow malicious code running in a PV guest VM to compromise the host
and malicious privileged code running in an HVM guest VM to crash the host.

These vulnerabilities affect all currently supported versions of Citrix
XenServer up to and including Citrix XenServer 7.4.

The following vulnerabilities have been addressed:

CVE-2017-5754: (High) Rogue data cache load, memory access permission check
performed after kernel memory read

CVE-2018-10982: (Medium) x86: vHPET interrupt injection errors

CVE-2018-8897: (High) x86: mishandling of debug exceptions

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Mitigating Factors

Customers with only HVM guest VMs with no untrustworthy privileged code running
have mitigated these issues.  Note that all Windows VMs are HVM guest VMs.

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What Customers Should Do

Hotfixes have been released to address these issues. Citrix strongly recommends
that affected customers install these hotfixes as soon as possible. The
hotfixes can be downloaded from the following locations:

Citrix XenServer 7.4: CTX234440 - https://support.citrix.com/article/CTX234440 

Citrix XenServer 7.3: CTX234439 - https://support.citrix.com/article/CTX234439 

Citrix XenServer 7.1 LTSR CU1: CTX234437 - https://support.citrix.com/article/

Citrix XenServer 7.0: CTX234436 - https://support.citrix.com/article/CTX234436 

Citrix XenServer 6.5 SP1: CTX234435 - https://support.citrix.com/article/

Citrix XenServer 6.2 SP1: CTX234434 - https://support.citrix.com/article/

Citrix XenServer 6.0.2 Common Criteria: CTX234433 - https://support.citrix.com/

In addition, following the publication of CVE-2017-5754, Citrix committed to
provide mitigations for this issue for the Citrix XenServer 7.2 release which
is now End of Life.  A hotfix for this release is available at Citrix XenServer
7.2: CTX234438 - https://support.citrix.com/article/CTX234438 

Note that, in line with previous statements, the hotfixes for the 6.x versions
of Citrix XenServer do not include mitigations for CVE-2017-5754.

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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/.

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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. 

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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

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|Date                         |Change                                         |
|8th May 2018                 |Initial Publication                            |

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