CVE-2023-5679
Description
A flaw was found in the bind package. This issue may allow an attacker to query in a DNS64 enabled resolver node with a domain name triggering a server-stale data, triggering a code assertion, and resulting in a crash of named processes. This can allow a remote unauthenticated user to cause a Denial Of Service in the DNS server.
Statement
The identified vulnerability in the BIND DNS server poses a important severity risk due to its potential to induce a Denial of Service (DoS) through a targeted exploitation of DNS64 functionality. Specifically, the flaw allows an attacker to send a crafted domain query that triggers a code assertion failure within the named process. This leads to a crash of the DNS server, disrupting its ability to resolve queries and maintain network operations. As a result, the DNS service becomes unavailable to legitimate users, impacting the integrity and availability of network services and potentially disrupting business operations or network communications. The exploitation of this vulnerability by an unauthenticated remote user underscores the urgent need for immediate patching and mitigation to safeguard DNS infrastructure against service outages.
Mitigation
This vulnerability can be mitigated by either disabled server-stale configuration, using both of the switches bellow in named configuration file:
1) set stale-cache-enable no;
2) set stale-answer-enable no;
Alternatively, disable the DNS64 option. Both mitigations should make the affected code unreachable, making it impossible to an attacker to exploit this vulnerability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker that can trigger an assert statement can still lead to a denial of service if the relevant code can be triggered by an attacker, and if the scope of the assert() extends beyond the attacker's own session.
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