CVE-2008-3963 in MySQL
Summary
by MITRE
MySQL 5.0 before 5.0.66, 5.1 before 5.1.26, and 6.0 before 6.0.6 does not properly handle a b (b single-quote single-quote) token, aka an empty bit-string literal, which allows remote attackers to cause a denial of service (daemon crash) by using this token in a SQL statement.
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Analysis
by VulDB Data Team • 12/22/2024
The vulnerability identified as CVE-2008-3963 represents a critical denial of service flaw in multiple versions of the MySQL database management system. This issue affects MySQL 5.0 versions prior to 5.0.66, MySQL 5.1 versions prior to 5.1.26, and MySQL 6.0 versions prior to 6.0.6. The vulnerability stems from improper handling of a specific SQL token known as the empty bit-string literal, which is represented as two consecutive single quotes b. This particular token sequence creates a parsing anomaly that can be exploited by remote attackers to crash the MySQL daemon service.
The technical flaw manifests when the MySQL parser encounters the b token in SQL statements, which should be interpreted as an empty bit-string literal. However, the parser fails to properly validate or handle this specific token sequence, leading to an unexpected state that causes the database daemon to terminate abruptly. This parsing error occurs at the core level of the SQL statement processing engine, where the system does not adequately account for edge cases involving bit-string literals. The vulnerability specifically exploits the database's inability to gracefully handle malformed or edge-case bit-string representations, causing memory corruption or internal state inconsistencies that result in process termination.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with a reliable method to perform denial of service attacks against MySQL installations. Remote attackers can craft malicious SQL statements containing the b token and execute them against vulnerable database instances, resulting in immediate daemon crashes that require manual intervention to restore service. This vulnerability affects database availability and can be particularly damaging in production environments where database uptime is critical for business operations. The attack vector requires no authentication, making it especially dangerous as any remote user with database access can exploit this flaw, potentially causing cascading failures in applications dependent on the affected database service.
The vulnerability maps directly to CWE-129, which covers improper validation of an input, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. Organizations should prioritize immediate patching of affected MySQL versions to address this vulnerability, as the fix involves updating to the patched versions that properly handle the empty bit-string literal token. System administrators should also implement monitoring solutions to detect unusual daemon termination patterns and consider network-level restrictions to limit SQL statement complexity for database users. Additionally, implementing proper input validation at the application layer can provide an additional defense mechanism against exploitation attempts, though the primary mitigation remains upgrading to patched MySQL versions that address the core parsing issue in the database engine's SQL statement processor.