CVE-2015-5722 in BIND
Summary
by MITRE
buffer.c in named in ISC BIND 9.x before 9.9.7-P3 and 9.10.x before 9.10.2-P4 allows remote attackers to cause a denial of service (assertion failure and daemon exit) by creating a zone containing a malformed DNSSEC key and issuing a query for a name in that zone.
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Analysis
by VulDB Data Team • 06/14/2022
The vulnerability identified as CVE-2015-5722 represents a critical buffer overflow condition affecting the Internet Systems Consortium BIND DNS server software. This flaw exists within the buffer.c component of BIND versions prior to 9.9.7-P3 and 9.10.2-P4, creating a significant security risk for organizations relying on DNS infrastructure. The vulnerability manifests when the named daemon processes zone data containing malformed DNSSEC keys, leading to an assertion failure that terminates the DNS service entirely.
The technical implementation of this vulnerability stems from inadequate input validation within the DNSSEC key processing pipeline. When a malicious actor constructs a zone file with malformed DNSSEC key data and subsequently queries for names within that zone, the named daemon fails to properly handle the malformed data structure. This condition triggers an assertion failure within the buffer.c module, causing the daemon to exit abruptly and resulting in a complete denial of service for legitimate DNS queries. The flaw operates at the core level of DNSSEC processing, where the software fails to properly validate key format and structure before attempting to process cryptographic operations.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with a reliable method for causing persistent DNS outages. Organizations utilizing affected BIND versions face the risk of sustained denial of service attacks that can compromise critical network infrastructure and applications dependent on DNS resolution. The vulnerability's remote exploitability means that attackers need only send specially crafted zone data and queries to affect the target system, making it particularly dangerous in environments where DNS servers handle external zone transfers or receive dynamic updates. This flaw directly relates to CWE-121, which describes heap-based buffer overflow conditions, and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
Mitigation strategies for CVE-2015-5722 require immediate deployment of patched BIND versions, specifically 9.9.7-P3 or later, and 9.10.2-P4 or later, which contain proper input validation for DNSSEC key data. Organizations should also implement network segmentation to limit exposure of DNS servers to untrusted networks and consider implementing additional monitoring for unusual DNS query patterns that might indicate exploitation attempts. The fix addresses the underlying buffer handling issue by ensuring that malformed DNSSEC keys are properly rejected before processing, preventing the assertion failure that leads to daemon termination. Security teams should also conduct thorough vulnerability assessments of their DNS infrastructure to identify any other potentially affected systems and ensure that all DNS servers are updated to patched versions to prevent exploitation.