Amazon Linux 2023 : python3-unbound, unbound, unbound-anchor (ALAS2023-2023-078)

medium Nessus Plugin ID 173079

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Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2023-078 advisory.

NLnet Labs Unbound, up to and including version 1.16.1 is vulnerable to a novel type of the ghost domain names attack. The vulnerability works by targeting an Unbound instance. Unbound is queried for a subdomain of a rogue domain name. The rogue nameserver returns delegation information for the subdomain that updates Unbound's delegation cache. This action can be repeated before expiry of the delegation information by querying Unbound for a second level subdomain which the rogue nameserver provides new delegation information. Since Unbound is a child-centric resolver, the ever-updating child delegation information can keep a rogue domain name resolvable long after revocation. From version 1.16.2 on, Unbound checks the validity of parent delegation records before using cached delegation information.
(CVE-2022-30698)

NLnet Labs Unbound, up to and including version 1.16.1, is vulnerable to a novel type of the ghost domain names attack. The vulnerability works by targeting an Unbound instance. Unbound is queried for a rogue domain name when the cached delegation information is about to expire. The rogue nameserver delays the response so that the cached delegation information is expired. Upon receiving the delayed answer containing the delegation information, Unbound overwrites the now expired entries. This action can be repeated when the delegation information is about to expire making the rogue delegation information ever- updating. From version 1.16.2 on, Unbound stores the start time for a query and uses that to decide if the cached delegation information can be overwritten. (CVE-2022-30699)

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.
(CVE-2022-3204)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Run 'dnf update unbound --releasever=2023.0.20230222 ' to update your system.

Plugin Details

Severity: Medium

ID: 173079

File Name: al2023_ALAS2023-2023-078.nasl

Version: 1.1

Type: local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 3/21/2023

Updated: 12/11/2024

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:N/A:N

CVSS Score Source: CVE-2022-30699

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:python3-unbound-debuginfo, p-cpe:/a:amazon:linux:unbound-anchor, p-cpe:/a:amazon:linux:unbound-anchor-debuginfo, p-cpe:/a:amazon:linux:unbound-devel, p-cpe:/a:amazon:linux:unbound-debugsource, p-cpe:/a:amazon:linux:unbound-libs, p-cpe:/a:amazon:linux:unbound-debuginfo, p-cpe:/a:amazon:linux:unbound-libs-debuginfo, p-cpe:/a:amazon:linux:unbound-utils, p-cpe:/a:amazon:linux:unbound-utils-debuginfo, p-cpe:/a:amazon:linux:unbound, cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:python3-unbound

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 2/17/2023

Vulnerability Publication Date: 8/1/2022

Reference Information

CVE: CVE-2022-30698, CVE-2022-30699, CVE-2022-3204

Detections

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