CVE-2005-0034 in BIND
Summary
by MITRE
An "incorrect assumption" in the authvalidated validator function in BIND 9.3.0, when DNSSEC is enabled, allows remote attackers to cause a denial of service (named server exit) via crafted DNS packets that cause an internal consistency test (self-check) to fail.
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Analysis
by VulDB Data Team • 07/05/2025
The vulnerability described in CVE-2005-0034 represents a critical flaw in the BIND 9.3.0 DNS server implementation that specifically affects systems with DNSSEC enabled. This issue stems from an incorrect assumption within the authvalidated validator function, which is responsible for validating DNSSEC signatures and ensuring the integrity of DNS responses. The flaw manifests when the server processes crafted DNS packets that trigger an internal consistency test failure, leading to a complete server crash and subsequent denial of service condition. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication or special privileges, making it a significant threat to DNS infrastructure availability.
The technical root cause of this vulnerability lies in the improper handling of DNSSEC validation logic within the authvalidated function. When DNSSEC is enabled, BIND performs extensive validation checks on DNS responses to ensure their authenticity and integrity. However, the validator function contains a logical error that fails to properly account for certain edge cases in DNS packet structures, particularly when dealing with malformed or crafted DNS records that contain invalid DNSSEC signatures or inconsistent data structures. This incorrect assumption leads to a scenario where legitimate validation procedures encounter unexpected conditions that cause the server to terminate its process rather than gracefully handle the error or reject the invalid data. The vulnerability specifically impacts the internal consistency checking mechanisms that BIND employs to verify the correctness of its own processing logic.
The operational impact of CVE-2005-0034 is severe and far-reaching for organizations relying on BIND DNS servers with DNSSEC enabled. A successful exploitation of this vulnerability can result in complete service disruption, forcing DNS servers to restart or crash entirely, which can cascade into widespread network outages affecting numerous services that depend on DNS resolution. This denial of service condition can persist until manual intervention occurs to restart the named service or apply patches, creating significant operational downtime. The vulnerability affects the core DNS server functionality and can potentially impact large-scale deployments including authoritative DNS servers, recursive resolvers, and caching servers that have DNSSEC enabled, making it particularly dangerous for internet infrastructure providers and enterprises that depend on reliable DNS services.
Organizations should implement immediate mitigations including disabling DNSSEC on affected BIND 9.3.0 servers until patches are applied, applying the official BIND security updates released by ISC, and implementing network-level protections such as rate limiting and packet filtering to reduce the impact of potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and CWE-248 for an abnormal termination that can lead to service disruption. Additionally, implementing proper monitoring and alerting for DNS server crashes or restarts can help detect exploitation attempts, while network segmentation and access controls can limit the potential attack surface. System administrators should also consider implementing redundant DNS infrastructure and failover mechanisms to minimize the impact of potential exploitation, as the vulnerability specifically targets the core validation logic that is fundamental to DNS server operation and security.