Citrix XenServer Multiple Vulnerabilities (CTX219378)

This script is Copyright (C) 2017 Tenable Network Security, Inc.


Synopsis :

A server virtualization platform installed on the remote host is
affected by multiple vulnerabilities.

Description :

The version of Citrix XenServer installed on the remote host is
missing a security hotfix. It is, therefore, affected by multiple
vulnerabilities :

- A flaw exists in x86 instruction CMPXCHG8B due to legacy
operand size overrides not being properly ignored when
handling prefixes. A guest attacker can exploit this to
disclose potentially sensitive information on the host
system. Note that 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.
(CVE-2016-9932)

- A denial of service vulnerability exists when a guest
asynchronously modifies its instruction stream to effect
the clearing of EFLAGS.IF. A guest attacker can exploit
this to cause the host to hang or crash.
(CVE-2016-10024)

- A denial of service vulnerability exists due to a NULL
pointer dereference flaw that is triggered when the
hvmemul_vmfunc() function pointer uses inappropriate
NULL checks before indirect function calls. A guest
attacker can exploit this to cause the hypervisor to
crash. Note that the ability of privileged-mode code in
HVM guest VMs to crash the host is restricted to AMD
systems running Citrix XenServer 7.0. (CVE-2016-10025)

See also :

https://support.citrix.com/article/CTX219378

Solution :

Apply the appropriate hotfix according to the vendor advisory.

Risk factor :

Medium / CVSS Base Score : 5.5
(CVSS2#AV:A/AC:L/Au:S/C:N/I:N/A:C)
CVSS Temporal Score : 4.5
(CVSS2#E:F/RL:OF/RC:ND)
Public Exploit Available : true

Family: Misc.

Nessus Plugin ID: 96778 ()

Bugtraq ID: 94863
95021
95026

CVE ID: CVE-2016-9932
CVE-2016-10024
CVE-2016-10025

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