Vulmon
Description of Problem
Security vulnerabilities have been identified in Citrix XenServer that may allow malicious code running within a guest VM to read a small part of hypervisor memory and allow privileged-mode code running within a guest VM to hang or crash the host.
These vulnerabilities affect all currently supported versions of Citrix XenServer up to and including Citrix XenServer 7.0.
The following vulnerabilities have been addressed:
- CVE-2016-9932 (Low): x86 CMPXCHG8B emulation fails to ignore operand size override
- CVE-2016-10024 (Medium): x86 PV guests may be able to mask interrupts
- CVE-2016-10025 (Low): missing NULL pointer check in VMFUNC emulation
Mitigating Factors
The ability to read a small amount of hypervisor memory is restricted to privileged-mode code in all guests except on Citrix XenServer 6.2 SP1 and 6.0.2CC where the attack may also be performed from non-privileged mode code in HVM guest VMs.
The ability for privileged-mode code in HVM guest VMs to crash the host is restricted to AMD systems running Citrix XenServer 7.0.
What Customers Should Do
Hotfixes have been released to address these issues. Citrix strongly recommends that affected customers install these hotfixes, which can be downloaded from the following locations:
Citrix XenServer 7.0: CTX219498 – https://support.citrix.com/article/CTX219498
Citrix XenServer 6.5 SP1: CTX219499 – https://support.citrix.com/article/CTX219499
Citrix XenServer 6.2 SP1: CTX219500 – https://support.citrix.com/article/CTX219500
Citrix XenServer 6.0.2 Common Criteria: CTX219501 – https://support.citrix.com/article/CTX219501
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 guidance on how to report security-related issues to Citrix, please see the following document: CTX081743 – Reporting Security Issues to Citrix
Changelog
| Date | Change |
| 21st December 2016 | Initial publishing |