Microsoft Windows up to Server 2016 Kerberos improper authentication

CVSS Meta Temp Score
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CTI Interest Score
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6.4$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Microsoft Windows up to Server 2016. This impacts an unknown function of the component Kerberos. Executing a manipulation can lead to improper authentication. This vulnerability is registered as CVE-2017-8495. It is possible to launch the attack remotely. No exploit is available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability classified as problematic was found in Microsoft Windows up to Server 2016 (Operating System). This vulnerability affects some unknown functionality of the component Kerberos. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Microsoft Windows 7 SP1, Windows Server 2008 SP2 and R2 SP1, Windows 8.1 and Windows RT 8.1, Windows Server 2012 and R2, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows an attacker to bypass Extended Protection for Authentication when Kerberos fails to prevent tampering with the SNAME field during ticket exchange, aka "Kerberos SNAME Security Feature Bypass Vulnerability".

The bug was discovered 07/11/2017. The weakness was published 07/11/2017 as KB4022746 as confirmed security update guide (Website). The advisory is shared for download at portal.msrc.microsoft.com. This vulnerability was named CVE-2017-8495 since 05/03/2017. The exploitation appears to be difficult. The attack can be initiated remotely. A single authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The advisory points out:

A security feature bypass vulnerability exists in Microsoft Windows when Kerberos fails to prevent tampering with the SNAME field during ticket exchange. An attacker who successfully exploited this vulnerability could use it to bypass Extended Protection for Authentication.

The vulnerability scanner Nessus provides a plugin with the ID 101365 (Windows 8.1 and Windows Server 2012 R2 July 2017 Security Updates), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Windows : Microsoft Bulletins and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 91499 (Microsoft Azure Stack 1809 Multiple Security Vulnerabilities).

Applying the patch KB4022746 is able to eliminate this problem. The bugfix is ready for download at catalog.update.microsoft.com. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (101365) and SecurityFocus (BID 99424†). Similar entries are available at VDB-4431, VDB-7953, VDB-10710 and VDB-10696. Once again VulDB remains the best source for vulnerability data.

Productinfo

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.7
VulDB Meta Temp Score: 6.6

VulDB Base Score: 5.0
VulDB Temp Score: 4.8
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 7.5
Vendor Vector (Microsoft): 🔍

NVD Base Score: 7.5
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

Class: Improper authentication
CWE: CWE-287
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 101365
Nessus Name: Windows 8.1 and Windows Server 2012 R2 July 2017 Security Updates
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 802136
OpenVAS Name: Microsoft Windows Multiple Vulnerabilites (KB4025344)
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: 🔍

Patch: KB4022746

Timelineinfo

05/03/2017 🔍
07/11/2017 +69 days 🔍
07/11/2017 +0 days 🔍
07/11/2017 +0 days 🔍
07/11/2017 +0 days 🔍
07/11/2017 +0 days 🔍
07/11/2017 +0 days 🔍
07/12/2017 +1 days 🔍
12/31/2020 +1268 days 🔍

Sourcesinfo

Vendor: microsoft.com
Product: microsoft.com

Advisory: KB4022746
Researcher: Jeffrey Eric Altman
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-8495 (🔍)
GCVE (CVE): GCVE-0-2017-8495
GCVE (VulDB): GCVE-100-103420

OVAL: 🔍

SecurityFocus: 99424 - Microsoft Windows Kerberos CVE-2017-8495 Security Bypass Vulnerability
SecurityTracker: 1038862

scip Labs: https://www.scip.ch/en/?labs.20161215
See also: 🔍

Entryinfo

Created: 07/12/2017 10:36
Updated: 12/31/2020 16:41
Changes: 07/12/2017 10:36 (92), 06/06/2020 07:30 (4), 12/31/2020 16:37 (3), 12/31/2020 16:41 (1)
Complete: 🔍
Cache ID: 216::103

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