XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x/4.7.x PV Pagetable Updater Host access control

CVSS Meta Temp Score
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CTI Interest Score
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8.4$0-$5k0.00

Summaryinfo

A vulnerability marked as critical has been reported in XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x/4.7.x. This affects an unknown part of the component PV Pagetable Updater. This manipulation causes access control (Host). This vulnerability is tracked as CVE-2016-6258. The attack is restricted to local execution. No exploit exists. It is recommended to apply a patch to fix this issue.

Detailsinfo

A vulnerability was found in XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x/4.7.x (Virtualization Software). It has been declared as critical. Affected by this vulnerability is an unknown code of the component PV Pagetable Updater. The manipulation with an unknown input leads to a access control vulnerability (Host). The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

The PV pagetable code in arch/x86/mm.c in Xen 4.7.x and earlier allows local 32-bit PV guest OS administrators to gain host OS privileges by leveraging fast-paths for updating pagetable entries.

The weakness was disclosed 07/26/2016 by Jeremie Boutoille with QUARKSLAB as XSA-182 as confirmed security advisory (Website). It is possible to read the advisory at xenbits.xen.org. This vulnerability is known as CVE-2016-6258 since 07/20/2016. The attack can be launched remotely. A single authentication is needed for exploitation. 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:

The PV pagetable code has fast-paths for making updates to pre-existing pagetable entries, to skip expensive re-validation in safe cases (e.g. clearing only Access/Dirty bits). The bits considered safe were too broad, and not actually safe.

The vulnerability scanner Nessus provides a plugin with the ID 92674 (FreeBSD : xen-kernel -- x86: Privilege escalation in PV guests (032aa524-5854-11e6-b334-002590263bf5) (Bunker Buster)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family FreeBSD Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 175798 (Debian Security Update for xen (DSA 3633-1)).

Applying a 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 (92674), SecurityFocus (BID 92131†) and SecurityTracker (ID 1036446†). The entries VDB-79748, VDB-87542, VDB-87720 and VDB-87769 are pretty similar. Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.8
VulDB Meta Temp Score: 8.6

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 8.8
NVD Vector: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

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

Physical: Partially
Local: Yes
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 92674
Nessus Name: FreeBSD : xen-kernel -- x86: Privilege escalation in PV guests (032aa524-5854-11e6-b334-002590263bf5) (Bunker Buster)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 60632
OpenVAS Name: Fedora Update for xen FEDORA-2016-0049aa6e5d
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

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

Timelineinfo

07/20/2016 🔍
07/26/2016 +6 days 🔍
07/26/2016 +0 days 🔍
07/26/2016 +0 days 🔍
07/26/2016 +0 days 🔍
07/27/2016 +1 days 🔍
08/02/2016 +6 days 🔍
08/02/2016 +0 days 🔍
03/13/2019 +953 days 🔍

Sourcesinfo

Vendor: citrix.com

Advisory: XSA-182
Researcher: Jeremie Boutoille
Organization: QUARKSLAB
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2016-6258 (🔍)
GCVE (CVE): GCVE-0-2016-6258
GCVE (VulDB): GCVE-100-90367

OVAL: 🔍

SecurityFocus: 92131 - Xen CVE-2016-6258 Privilege Escalation Vulnerability
SecurityTracker: 1036446

See also: 🔍

Entryinfo

Created: 07/27/2016 13:22
Updated: 03/13/2019 19:40
Changes: 07/27/2016 13:22 (76), 03/13/2019 19:40 (13)
Complete: 🔍
Cache ID: 216:3ED:103

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