CVE-2016-2776 in BIND
Summary
by MITRE
buffer.c in named in ISC BIND 9 before 9.9.9-P3, 9.10.x before 9.10.4-P3, and 9.11.x before 9.11.0rc3 does not properly construct responses, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a crafted query.
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Analysis
by VulDB Data Team • 12/27/2024
The vulnerability identified as CVE-2016-2776 represents a critical buffer management flaw within the Internet Systems Consortium BIND DNS server software. This issue affects multiple versions of the widely deployed DNS resolver, specifically targeting ISC BIND versions prior to 9.9.9-P3, 9.10.4-P3, and 9.11.0rc3. The flaw manifests in the buffer.c component of the named daemon, which is responsible for processing DNS queries and constructing appropriate responses. The vulnerability stems from improper handling of DNS response construction, creating a scenario where malformed input can trigger unexpected behavior in the software's memory management systems.
The technical exploitation of this vulnerability occurs when remote attackers craft specially designed DNS queries that, when processed by the affected BIND versions, cause the daemon to encounter assertion failures. These assertion failures represent internal consistency checks that programmers implement to detect programming errors during development. When such assertions fail in a production environment, they typically result in the daemon terminating abruptly, leading to a complete denial of service condition. The flaw essentially allows an attacker to send a malicious query that causes the named process to crash and restart, effectively disrupting DNS services for all clients relying on that server.
From an operational perspective, this vulnerability poses significant risks to organizations that depend on BIND for their DNS infrastructure. The remote nature of the attack means that any system running vulnerable BIND versions is potentially exposed to exploitation from anywhere on the internet. The denial of service impact is severe as DNS services form the backbone of internet connectivity, and disruptions can cascade across entire networks, affecting email services, web browsing, and other internet-dependent applications. The vulnerability can be exploited with minimal resources and technical expertise, making it particularly dangerous in environments where DNS servers are not properly monitored or patched.
The underlying cause of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which addresses out-of-bounds read vulnerabilities. These classifications indicate that the flaw involves improper handling of memory boundaries during buffer operations. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers Network Denial of Service attacks, and T1071.004, covering application layer protocol usage. The attack chain typically involves reconnaissance to identify vulnerable systems followed by the delivery of crafted DNS queries designed to trigger the assertion failure.
Mitigation strategies for CVE-2016-2776 primarily focus on immediate patching of affected systems with the appropriate BIND releases containing the fix. Organizations should prioritize updating their DNS infrastructure to versions 9.9.9-P3, 9.10.4-P3, or 9.11.0rc3, depending on their current version. Additionally, implementing network-level protections such as DNS query filtering and rate limiting can help reduce the impact of potential attacks. System administrators should also consider implementing monitoring solutions that can detect unusual patterns of DNS query processing that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date DNS infrastructure and the potential consequences of failing to apply security patches promptly.