CVE-2015-8705 in BIND
Summary
by MITRE
buffer.c in named in ISC BIND 9.10.x before 9.10.3-P3, when debug logging is enabled, allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit, or daemon crash) or possibly have unspecified other impact via (1) OPT data or (2) an ECS option.
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Analysis
by VulDB Data Team • 07/03/2022
The vulnerability identified as CVE-2015-8705 affects the Internet Systems Consortium BIND DNS server version 9.10.x before 9.10.3-P3 and represents a critical buffer overflow condition that can be exploited remotely to cause denial of service or potentially more severe impacts. This flaw exists within the buffer.c file of the named daemon and specifically manifests when debug logging functionality is enabled, making it particularly dangerous in environments where debugging capabilities are active. The vulnerability stems from inadequate input validation and memory management when processing certain DNS option data structures, creating opportunities for attackers to craft malicious packets that trigger the flaw through either OPT data or ECS (EDNS Client Subnet) options.
The technical implementation of this vulnerability involves the manipulation of DNS protocol extensions that are commonly used for various operational purposes including DNSSEC validation and client subnet information handling. When debug logging is enabled, the named daemon processes these DNS options with insufficient boundary checking, allowing an attacker to provide malformed data that exceeds allocated buffer space. The REQUIRE assertion failure occurs when the daemon encounters data that violates expected parameter constraints, causing the process to terminate abruptly. This mechanism operates under CWE-121, which classifies buffer overflow conditions in heap-based buffers, and specifically aligns with CWE-787, which addresses out-of-bounds write conditions. The vulnerability can be leveraged through the attacker-controlled DNS packet format, where the malicious data is embedded within the OPT or ECS option fields that are part of the extended DNS protocol.
From an operational perspective, this vulnerability presents significant risk to DNS infrastructure as it can be exploited without authentication and can be delivered through standard DNS queries. The impact ranges from simple daemon termination to potential system crashes that can disrupt DNS resolution services for extended periods. Organizations running ISC BIND 9.10.x versions with debug logging enabled are particularly vulnerable, as the flaw requires no special privileges to exploit and can be executed through normal DNS traffic. The vulnerability has been classified under the MITRE ATT&CK framework as part of the T1499.004 technique related to Network Denial of Service, specifically targeting DNS services. The daemon crash or exit behavior can result in cascading failures when DNS resolution is critical for other network services, potentially affecting large portions of network infrastructure that depend on proper DNS functionality for their operations.
The recommended mitigation strategies include immediate patching to ISC BIND version 9.10.3-P3 or later, which addresses the buffer overflow conditions through proper input validation and memory boundary checks. Organizations should also disable debug logging in production environments where this vulnerability can be exploited, as the flaw specifically requires debug mode to be active. Network segmentation and monitoring solutions should be implemented to detect and alert on unusual DNS traffic patterns that might indicate exploitation attempts. Additionally, implementing DNS security extensions such as DNSSEC and configuring proper access controls to limit DNS query sources can reduce the attack surface. The vulnerability demonstrates the importance of proper memory management in network services and highlights how seemingly benign debugging features can create critical security weaknesses when not properly secured. Regular security assessments of DNS infrastructure should include verification of logging configurations and patch management processes to prevent similar vulnerabilities from affecting operational systems.