CVE-2017-3142 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 may be able to circumvent TSIG authentication of AXFR requests via a carefully constructed request packet. A server that relies solely on TSIG keys for protection with no other ACL protection could be manipulated into: providing an AXFR of a zone to an unauthorized recipient or accepting bogus NOTIFY packets. 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-2017-3142 represents a critical authentication bypass flaw within the Internet Systems Consortium BIND DNS server implementation. This issue specifically targets the TSIG (Transaction Signature) authentication mechanism that BIND uses to secure zone transfer operations and notifications. The flaw enables an attacker with network access to a DNS server and knowledge of a valid TSIG key name to manipulate the authentication process during AXFR (Authoritative Zone Transfer) requests. This vulnerability operates at the protocol level and exploits weaknesses in how BIND handles TSIG validation during zone transfer operations, potentially allowing unauthorized access to sensitive DNS zone data.
The technical implementation of this vulnerability stems from improper validation of TSIG signatures during AXFR request processing. When a DNS server receives an AXFR request, it should validate the TSIG signature using the associated key name and algorithm to ensure the request originates from an authorized source. However, the flaw in BIND versions 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, 9.9.3-S1 through 9.9.10-S2, and 9.10.5-S1 through 9.10.5-S2 allows an attacker to craft malicious request packets that bypass this validation mechanism. The vulnerability is particularly concerning because it can be exploited by an attacker who has already gained access to a valid TSIG key name, which can be obtained through various means including network monitoring or previous successful authentication attempts.
The operational impact of this vulnerability extends beyond simple unauthorized zone access, as it fundamentally undermines the security model of DNS zone transfers. An attacker who successfully exploits this vulnerability can either provide unauthorized access to complete DNS zone data to malicious parties or accept fraudulent NOTIFY packets that could lead to further attacks including DNS cache poisoning or denial of service conditions. The vulnerability particularly affects configurations that rely solely on TSIG keys for protection without additional access control lists or network-level restrictions. This creates a dangerous scenario where a single compromised TSIG key name can provide attackers with complete control over zone data distribution and notification mechanisms. Organizations using BIND servers without proper additional security measures face significant risk of data exposure and potential service disruption.
Mitigation strategies for CVE-2017-3142 require immediate implementation of multiple defensive measures to protect DNS infrastructure. The primary recommendation involves upgrading affected BIND server versions to patched releases that address the TSIG validation flaw. Organizations should also implement additional access control mechanisms beyond TSIG authentication, including network-level access control lists, IP address restrictions, and proper firewall configurations to limit access to authoritative DNS servers. The implementation of proper monitoring and logging of zone transfer activities can help detect unauthorized access attempts and potential exploitation of this vulnerability. Security practitioners should also consider implementing network segmentation to isolate DNS servers from general network traffic and ensure that TSIG keys are properly managed with appropriate key rotation policies. This vulnerability aligns with CWE-287 (Improper Authentication) and can be mapped to ATT&CK technique T1071.004 (Application Layer Protocol: DNS) in threat modeling contexts, representing a significant risk to network infrastructure security and requiring immediate remediation to prevent potential widespread impact on DNS resolution services and data confidentiality.
The vulnerability demonstrates how authentication bypass flaws in critical infrastructure components can have cascading security implications, particularly in environments where DNS servers serve as foundational elements of network security. The fact that this vulnerability affects multiple versions of BIND across different release streams indicates a persistent issue in the authentication implementation that required coordinated patching efforts across the software ecosystem. Organizations should conduct comprehensive vulnerability assessments of their DNS infrastructure to identify all affected systems and implement layered security controls to prevent exploitation of this and similar authentication bypass vulnerabilities.