ISC BIND up to 9.17.1 TSIG tsig.c Message assertion

Summaryinfo

A vulnerability described as problematic has been identified in ISC BIND up to 9.17.1. Affected is an unknown function of the file tsig.c of the component TSIG Handler. Executing a manipulation as part of Message can lead to assertion. This vulnerability is registered as CVE-2020-8617. The attack needs to be launched locally. Furthermore, an exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in ISC BIND up to 9.17.1 (Domain Name Software). This vulnerability affects an unknown code block of the file tsig.c of the component TSIG Handler. The manipulation as part of a Message leads to a assertion vulnerability. The CWE definition for the vulnerability is CWE-617. The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary. As an impact it is known to affect availability. CVE summarizes:

Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In releases of BIND dating from March 2018 and after, an assertion check in tsig.c detects this inconsistent state and deliberately exits. Prior to the introduction of the check the server would continue operating in an inconsistent state, with potentially harmful results.

The weakness was published 05/19/2020 (oss-sec). The advisory is shared for download at openwall.com. This vulnerability was named CVE-2020-8617 since 02/05/2020. The attack needs to be approached locally. No form of authentication is required for a successful exploitation. Technical details and also a public exploit are known. The advisory points out:

An error in BIND code which checks the validity of messages containing TSIG resource records can be exploited by an attacker to trigger an assertion failure in tsig.c, resulting in denial of service to clients.

It is possible to download the exploit at packetstormsecurity.com. It is declared as proof-of-concept. The vulnerability scanner Nessus provides a plugin with the ID 236577 (Alibaba Cloud Linux 3 : 0025: bind (ALINUX3-SA-2021:0025)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.11.19, 9.14.12 or 9.16.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (48521) and Tenable (236577). Similar entry is available at VDB-155439. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Domain Name Software

Vendor

• ISC

Name

• BIND

Version

• 9.0
• 9.1
• 9.2
• 9.3
• 9.4
• 9.5
• 9.6
• 9.7
• 9.8
• 9.9
• 9.10
• 9.11
• 9.11.0
• 9.11.1
• 9.11.2
• 9.11.3
• 9.11.4
• 9.11.5
• 9.11.6
• 9.11.7
• 9.11.8
• 9.11.9
• 9.11.10
• 9.11.11
• 9.11.12
• 9.11.13
• 9.11.14
• 9.11.15
• 9.11.16
• 9.11.17
• 9.11.18
• 9.12
• 9.12.4-P2
• 9.13
• 9.14
• 9.14.0
• 9.14.1
• 9.14.2
• 9.14.3
• 9.14.4
• 9.14.5
• 9.14.6
• 9.14.7
• 9.14.8
• 9.14.9
• 9.14.10
• 9.14.11
• 9.15
• 9.16.0
• 9.16.1
• 9.16.2
• 9.17.0
• 9.17.1

License

• open-source

Website

• Vendor: https://www.isc.org/

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion