CVE-2017-3143 in BIND
Summary
by MITRE
An attacker who is able to send and receive messages to an authoritative DNS server and who has knowledge of a valid TSIG key name for the zone and service being targeted may be able to manipulate BIND into accepting an unauthorized dynamic update. Affects BIND 9.4.0->9.8.8, 9.9.0->9.9.10-P1, 9.10.0->9.10.5-P1, 9.11.0->9.11.1-P1, 9.9.3-S1->9.9.10-S2, 9.10.5-S1->9.10.5-S2.
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Analysis
by VulDB Data Team • 12/09/2022
The vulnerability described in CVE-2017-3143 represents a critical authorization bypass flaw within the Berkeley Internet Name Domain (BIND) software that affects multiple versions of the DNS server implementation. This security weakness specifically targets the dynamic update functionality of BIND servers, creating a scenario where an attacker with network access and knowledge of valid TSIG key names can manipulate the authoritative DNS server into accepting unauthorized dynamic updates. The flaw stems from insufficient validation mechanisms during the dynamic update process, allowing malicious actors to exploit the trust relationship established through TSIG (Transaction Signature) authentication. This vulnerability is particularly dangerous because it leverages legitimate authentication mechanisms to gain unauthorized access to DNS zone data modification capabilities, effectively undermining the security model that BIND relies upon for protecting zone integrity.
The technical implementation of this vulnerability involves a specific flaw in how BIND validates dynamic update requests when TSIG authentication is used. When a DNS server receives a dynamic update request, it should verify both the authenticity of the TSIG signature and ensure that the update request is properly authorized for the specific zone and service being modified. However, in affected versions of BIND, the validation process fails to properly check the authorization context associated with the TSIG key name, allowing attackers to potentially bypass these security checks. The vulnerability affects a broad range of BIND versions including 9.4.0 through 9.8.8, 9.9.0 through 9.9.10-P1, 9.10.0 through 9.10.5-P1, 9.11.0 through 9.11.1-P1, and several intermediate versions, indicating a widespread issue that has persisted across multiple major releases. The flaw essentially allows an attacker to perform unauthorized DNS zone modifications, potentially leading to DNS cache poisoning, service disruption, or complete domain compromise.
The operational impact of CVE-2017-3143 extends beyond simple unauthorized access to DNS zone data, creating significant risks for organizations relying on BIND as their authoritative DNS server. An attacker who successfully exploits this vulnerability could modify DNS records to redirect traffic to malicious servers, implement DNS cache poisoning attacks, or disrupt critical network services that depend on accurate DNS resolution. The attack requires minimal prerequisites compared to many other DNS vulnerabilities, as it only necessitates the ability to send and receive DNS messages to the target server and knowledge of a valid TSIG key name, which may be obtained through various means such as network monitoring, social engineering, or previous security breaches. This makes the vulnerability particularly attractive to attackers and increases the potential for widespread exploitation across networks that have dynamic DNS update capabilities enabled.
Organizations affected by this vulnerability should prioritize immediate remediation through official software updates from ISC (Internet Systems Consortium) and implement additional security controls to mitigate potential exploitation attempts. The recommended mitigation strategy involves upgrading to BIND versions that contain the fix for this vulnerability, specifically versions 9.9.10-P2, 9.10.5-P2, 9.11.1-P2, and the corresponding releases in the 9.9.3-S2 and 9.10.5-S2 series. Security administrators should also consider implementing network-level controls to restrict access to DNS update ports and services, particularly when dynamic updates are not required for the specific zone. Additionally, organizations should review their TSIG key management practices to ensure that key names and credentials are properly secured and rotated regularly. From an operational security perspective, implementing monitoring for unusual DNS update activity and establishing proper access controls for TSIG keys can significantly reduce the risk of exploitation. This vulnerability aligns with CWE-284 (Improper Access Control) and can be mapped to ATT&CK technique T1071.004 (Application Layer Protocol: DNS) in threat modeling frameworks, highlighting the importance of proper authorization validation in DNS server implementations.