Unbound up to 1.16.2 Resolver NRDelegation denial of service

Summaryinfo

A vulnerability categorized as problematic has been discovered in Unbound up to 1.16.2. Affected by this vulnerability is an unknown functionality of the component Resolver. The manipulation results in denial of service. This vulnerability is identified as CVE-2022-3204. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Unbound up to 1.16.2. It has been classified as problematic. Affected is an unknown functionality of the component Resolver. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. CVE summarizes:

A vulnerability named 'Non-Responsive Delegation Attack' (NRDelegation Attack) has been discovered in various DNS resolving software. The NRDelegation Attack works by having a malicious delegation with a considerable number of non responsive nameservers. The attack starts by querying a resolver for a record that relies on those unresponsive nameservers. The attack can cause a resolver to spend a lot of time/resources resolving records under a malicious delegation point where a considerable number of unresponsive NS records reside. It can trigger high CPU usage in some resolver implementations that continually look in the cache for resolved NS records in that delegation. This can lead to degraded performance and eventually denial of service in orchestrated attacks. Unbound does not suffer from high CPU usage, but resources are still needed for resolving the malicious delegation. Unbound will keep trying to resolve the record until hard limits are reached. Based on the nature of the attack and the replies, different limits could be reached. From version 1.16.3 on, Unbound introduces fixes for better performance when under load, by cutting opportunistic queries for nameserver discovery and DNSKEY prefetching and limiting the number of times a delegation point can issue a cache lookup for missing records.

The weakness was released 09/27/2022. The advisory is shared for download at nlnetlabs.nl. This vulnerability is traded as CVE-2022-3204 since 09/13/2022. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 211266 (Fedora 37 : unbound (2022-1326d2815c)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.16.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (211266) and CERT Bund (WID-SEC-2023-1185). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Fedora Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• Gentoo Linux
• SUSE openSUSE
• Red Hat OpenShift
• RESF Rocky Linux

Productinfo

Name

• Unbound

Version

• 1.16.0
• 1.16.1
• 1.16.2

CPE 2.3info

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CPE 2.2info

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

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