CVE-2012-4244 in BIND
Summary
by MITRE
ISC BIND 9.x before 9.7.6-P3, 9.8.x before 9.8.3-P3, 9.9.x before 9.9.1-P3, and 9.4-ESV and 9.6-ESV before 9.6-ESV-R7-P3 allows remote attackers to cause a denial of service (assertion failure and named daemon exit) via a query for a long resource record.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability described in CVE-2012-4244 represents a critical denial of service flaw affecting ISC BIND DNS server software across multiple version ranges. This issue specifically impacts versions prior to the mentioned patches, creating a scenario where remote attackers can exploit a weakness in the named daemon's handling of DNS queries. The flaw manifests when a malicious query containing an excessively long resource record is submitted to the DNS server, triggering an assertion failure that ultimately causes the named daemon to terminate unexpectedly. This type of vulnerability falls under the category of software fault tolerance issues and directly impacts the availability of DNS services that organizations rely upon for network operations and domain name resolution.
The technical mechanism behind this vulnerability involves the improper handling of resource record data structures within the BIND software implementation. When the named daemon processes a query for a resource record that exceeds predetermined length limits, the internal assertion checks fail to properly validate the data structure before proceeding with processing. This assertion failure represents a fundamental breakdown in the software's error handling mechanisms, as the system does not gracefully manage malformed or excessively long input data. The vulnerability specifically targets the assertion failure condition that occurs during resource record processing, where the software's internal validation logic encounters a condition it cannot handle properly, leading to an immediate daemon termination. This behavior aligns with CWE-617, which describes reachable assertions that can be triggered by external input, making it particularly dangerous in network-facing services.
The operational impact of CVE-2012-4244 extends far beyond simple service disruption, as DNS servers form the backbone of internet infrastructure and network operations. When the named daemon crashes due to this assertion failure, it creates a cascading effect that can impact numerous dependent services, including web applications, email systems, and internal network operations that rely on proper DNS resolution. Organizations experiencing this vulnerability may face extended downtime, service degradation, and potential security implications if attackers systematically exploit the flaw to create persistent denial of service conditions. The vulnerability's remote exploitability means that attackers need not have physical access to the system or network, making it particularly concerning for organizations with publicly accessible DNS servers. This attack vector aligns with ATT&CK technique T1499.004, which describes denial of service through resource exhaustion and assertion failures, demonstrating how such vulnerabilities can be leveraged for broader operational disruption.
Mitigation strategies for CVE-2012-4244 primarily focus on immediate software patching and implementation of defensive network configurations. Organizations should prioritize updating their BIND installations to versions that include the security fixes released in the patch levels mentioned in the CVE description, specifically upgrading to BIND 9.7.6-P3, 9.8.3-P3, 9.9.1-P3, or the appropriate ESV releases. Beyond patching, network administrators should implement additional defensive measures such as rate limiting and query filtering to reduce the impact of malformed queries reaching the authoritative DNS servers. Implementing proper monitoring and alerting systems can help detect unusual query patterns that might indicate exploitation attempts, while network segmentation and access control measures can limit the potential attack surface. The vulnerability's characteristics also suggest that implementing proper input validation and boundary checking mechanisms at the application level could provide additional protection against similar issues in other software components. Organizations should also consider implementing DNS server hardening practices and regularly reviewing their DNS configurations to ensure they align with security best practices established by industry standards and frameworks such as NIST SP 800-53 and ISO 27001.