CVE-2003-0073 in MySQL
Summary
by MITRE
Double-free vulnerability in mysqld for MySQL before 3.23.55 allows attackers with MySQL access to cause a denial of service (crash) via mysql_change_user.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 05/12/2019
The vulnerability identified as CVE-2003-0073 represents a critical double-free memory error within the mysqld daemon of MySQL database systems prior to version 3.23.55. This flaw exists in the mysql_change_user function which is used to switch user contexts within the database connection. The double-free condition occurs when the system attempts to release the same memory block twice during the execution of the mysql_change_user operation, creating a scenario where memory corruption can occur. Such vulnerabilities are particularly dangerous as they can lead to unpredictable system behavior and are often exploited for more severe attacks beyond simple denial of service.
The technical implementation of this vulnerability stems from improper memory management within the MySQL server's internal code structure. When a user executes the mysql_change_user function, the system allocates memory for user context structures and subsequently frees them. However, due to flawed logic in the memory deallocation process, the same memory segment gets freed twice, leading to heap corruption. This memory corruption can cause the mysqld process to crash or behave unpredictably, resulting in a denial of service condition that prevents legitimate users from accessing the database. The vulnerability is particularly concerning because it requires only existing MySQL access privileges to exploit, making it accessible to users who already have legitimate database connections.
From an operational perspective, this vulnerability creates significant risk for database environments that rely on MySQL versions prior to 3.23.55. The impact extends beyond simple service disruption as the double-free condition can potentially be leveraged for more sophisticated attacks. An attacker with legitimate MySQL access can repeatedly invoke the mysql_change_user function to trigger the memory corruption, causing the database server to crash and restart. This can lead to extended downtime for applications dependent on the database, data loss from abrupt termination, and potential information disclosure through the corrupted memory state. The vulnerability is classified under CWE-415 as an double free condition, which is a well-known weakness in memory management that can lead to arbitrary code execution in some cases.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to denial of service and privilege escalation. While the initial access requirement is relatively low, the potential for escalation exists through the memory corruption that can be leveraged in subsequent attack phases. Organizations should prioritize patching affected MySQL installations to prevent exploitation, as the vulnerability does not require special privileges beyond existing database access. The recommended mitigation strategy involves upgrading to MySQL version 3.23.55 or later, where the memory management issues have been resolved. Additionally, implementing proper access controls and monitoring for unusual mysql_change_user function calls can help detect potential exploitation attempts. Security teams should also consider deploying intrusion detection systems that can identify patterns of memory corruption attempts and maintain comprehensive backup and recovery procedures to minimize downtime in case of successful exploitation.