krb5 certauth Interface up to 1.16.0 Impersonation improper authentication

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3	$0-$5k	0.00

Summaryinfo

A vulnerability was found in krb5 certauth Interface up to 1.16.0. It has been declared as critical. This affects an unknown part. Executing a manipulation can lead to improper authentication (Impersonation). This vulnerability is tracked as CVE-2017-7562. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in krb5 certauth Interface up to 1.16.0. This vulnerability affects some unknown processing. The manipulation with an unknown input leads to a improper authentication vulnerability (Impersonation). 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:

An authentication bypass flaw was found in the way krb5's certauth interface before 1.16.1 handled the validation of client certificates. A remote attacker able to communicate with the KDC could potentially use this flaw to impersonate arbitrary principals under rare and erroneous circumstances.

The bug was discovered 08/25/2017. The weakness was disclosed 07/26/2018 as confirmed bug report (Bugzilla). The advisory is shared for download at bugzilla.redhat.com. This vulnerability was named CVE-2017-7562 since 04/05/2017. The exploitation appears to be easy. The attack can be initiated remotely. Required for exploitation is a single authentication. There are neither technical details nor an exploit publicly available.

The vulnerability was handled as a non-public zero-day exploit for at least 258 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 109689 (Amazon Linux 2 : krb5 (ALAS-2018-1010)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Amazon Linux Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 157689 (Oracle Enterprise Linux Security Update for krb5 (ELSA-2018-0666)).

Upgrading to version 1.16.1 eliminates this vulnerability. A possible mitigation has been published before and not just after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (109689) and SecurityFocus (BID 100511†). The entry VDB-105189 is pretty similar. Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• krb5 certauth Interface

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16.0

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 6.5
NVD Vector: 🔍

CNA Base Score: 6.5
CNA Vector (Red Hat, Inc.): 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Name: Impersonation
Class: Improper authentication / Impersonation
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: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 109689
Nessus Name: Amazon Linux 2 : krb5 (ALAS-2018-1010)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: krb5 certauth Interface 1.16.1
Patch: github.com

Timelineinfo

04/05/2017 🔍
08/25/2017 +142 days 🔍
08/25/2017 +0 days 🔍
05/10/2018 +257 days 🔍
05/11/2018 +1 days 🔍
07/26/2018 +75 days 🔍
07/26/2018 +0 days 🔍
07/26/2018 +0 days 🔍
04/25/2023 +1734 days 🔍

Sourcesinfo

Advisory: RHSA-2018:0666
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-7562 (🔍)
GCVE (CVE): GCVE-0-2017-7562
GCVE (VulDB): GCVE-100-122212
SecurityFocus: 100511 - MIT krb5 CVE-2017-7562 Authentication Bypass Vulnerability

See also: 🔍

Entryinfo

Created: 07/26/2018 20:04
Updated: 04/25/2023 20:24
Changes: 07/26/2018 20:04 (71), 03/10/2020 13:46 (4), 04/25/2023 20:16 (5), 04/25/2023 20:24 (11)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

Discussion

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