XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x on AMD x86 access control

CVSS Meta Temp Score
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CTI Interest Score
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3.7$0-$5k0.00

Summaryinfo

A vulnerability was found in XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x on AMD x86. It has been classified as problematic. Affected by this issue is some unknown functionality. Performing a manipulation results in access control. This vulnerability is known as CVE-2016-3158. Attacking locally is a requirement. No exploit is available. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x on AMD x86 (Virtualization Software). It has been classified as problematic. This affects an unknown code block. The manipulation with an unknown input leads to a access control vulnerability. CWE is classifying the issue as CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. This is going to have an impact on confidentiality.

The weakness was published 03/24/2016 by Jan Beulich with SuSE as XSA-172 as confirmed security advisory (Website). It is possible to read the advisory at xenbits.xen.org. This vulnerability is uniquely identified as CVE-2016-3158 since 03/15/2016. Attacking locally is a requirement. The requirement for exploitation is a authentication. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK. The advisory points out:

There is a workaround in Xen to deal with the fact that AMD CPUs don't load the x86 registers FIP (and possibly FCS), FDP (and possibly FDS), and FOP from memory (via XRSTOR or FXRSTOR) when there is no pending unmasked exception. (See XSA-52.) However, this workaround does not cover all possible input cases. This is because writes to the hardware FSW.ES bit, which the current workaround is based on, are ignored; instead, the CPU calculates FSW.ES from the pending exception and exception mask bits. Xen therefore needs to do the same. Note that part of said workaround was the subject of XSA-52. This can leak register contents from one guest to another. The registers in question are the FPU instruction and data pointers and opcode.

The vulnerability scanner Nessus provides a plugin with the ID 93296 (SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2016:2093-1) (Bunker Buster)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family SuSE Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 370023 (Citrix XenServer Security Update (CTX209443)).

Applying the patch xsa172.patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (93296), SecurityFocus (BID 85714†), SecurityTracker (ID 1035435†) and Vulnerability Center (SBV-58186†). Similar entries are available at VDB-76871, VDB-81025, VDB-81556 and VDB-82557. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.8
VulDB Meta Temp Score: 3.7

VulDB Base Score: 3.8
VulDB Temp Score: 3.7
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 3.8
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
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Exploitinginfo

Class: Access control
CWE: CWE-284 / CWE-266
CAPEC: 🔍
ATT&CK: 🔍

Physical: Partially
Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 93296
Nessus Name: SUSE SLED12 / SLES12 Security Update : xen (SUSE-SU-2016:2093-1) (Bunker Buster)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 867773
OpenVAS Name: Fedora Update for xen FEDORA-2016-5
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
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Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Patch: xsa172.patch

Timelineinfo

03/15/2016 🔍
03/24/2016 +9 days 🔍
03/24/2016 +0 days 🔍
03/24/2016 +0 days 🔍
03/29/2016 +5 days 🔍
03/31/2016 +2 days 🔍
04/13/2016 +12 days 🔍
04/13/2016 +0 days 🔍
04/14/2016 +1 days 🔍
09/02/2016 +141 days 🔍
07/11/2022 +2138 days 🔍

Sourcesinfo

Vendor: citrix.com

Advisory: XSA-172
Researcher: Jan Beulich
Organization: SuSE
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2016-3158 (🔍)
GCVE (CVE): GCVE-0-2016-3158
GCVE (VulDB): GCVE-100-81555

OVAL: 🔍

SecurityFocus: 85714 - Xen CVE-2016-3158 Information Disclosure Vulnerability
SecurityTracker: 1035435
Vulnerability Center: 58186 - Xen 4.x arch/x86/xstate.c on AMD64 Processors Local Register Content Information Disclosure Vulnerability, Low

See also: 🔍

Entryinfo

Created: 03/31/2016 16:48
Updated: 07/11/2022 17:07
Changes: 03/31/2016 16:48 (81), 02/04/2019 15:11 (13), 07/11/2022 17:07 (3)
Complete: 🔍
Cache ID: 216:C99:103

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