CVE-2002-1221 in BIND
Summary
by MITRE
BIND 8.x through 8.3.3 allows remote attackers to cause a denial of service (crash) via SIG RR elements with invalid expiry times, which are removed from the internal BIND database and later cause a null dereference.
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Analysis
by VulDB Data Team • 09/07/2025
The vulnerability identified as CVE-2002-1221 affects the Berkeley Internet Name Domain software version 8.x through 8.3.3, representing a critical denial of service flaw that can be exploited remotely by attackers. This vulnerability specifically targets the handling of SIG resource record elements within the BIND DNS server implementation. The flaw manifests when the system processes SIG records containing invalid expiry times, which creates a cascade of issues within the internal database management system. The SIG records in question are designed to provide security through DNS security extensions, but their improper handling creates an exploitable condition that can crash the entire DNS service.
The technical implementation of this vulnerability stems from how BIND processes and stores SIG resource records within its internal database structure. When the system encounters SIG records with invalid expiry times, it removes these records from the database as part of its normal processing. However, the removal process does not properly account for references to these records in other parts of the system's memory structures. This creates a scenario where the database entries are marked as deleted but remain referenced elsewhere, leading to a null pointer dereference when the system attempts to access these invalid references during subsequent processing cycles. The null dereference condition causes the BIND process to crash and terminate unexpectedly, resulting in a complete denial of service for the affected DNS server.
This vulnerability directly maps to CWE-476 which describes null pointer dereference conditions in software implementations. The operational impact of CVE-2002-1221 extends beyond simple service disruption as DNS servers form the backbone of internet infrastructure, making this a particularly dangerous flaw. When exploited, the vulnerability can cause widespread network disruption as the affected DNS server becomes unavailable, preventing clients from resolving domain names and accessing internet resources. The attack vector requires only remote access to send malformed SIG records to the target DNS server, making it easily exploitable without requiring privileged access or complex attack chains. This vulnerability falls under the ATT&CK technique T1499.004 for network denial of service attacks, specifically targeting the availability of network services through resource exhaustion or process termination.
The mitigation strategies for this vulnerability involve immediate patching of affected BIND versions to 8.3.4 or later, which includes proper handling of invalid expiry times in SIG records. Organizations should also implement network monitoring to detect unusual DNS traffic patterns that might indicate exploitation attempts, particularly around SIG record processing. Additionally, implementing proper input validation and sanitization measures for DNS record processing can help prevent similar issues in other software components. The vulnerability highlights the importance of proper memory management and database consistency checking in DNS server implementations, as well as the need for comprehensive testing of edge cases in security-related protocol handling. Network administrators should also consider implementing redundant DNS services and proper failover mechanisms to minimize the impact of such denial of service events on overall network availability.