CVE-2012-4452 in MySQL
Summary
by MITRE
MySQL 5.0.88, and possibly other versions and platforms, allows local users to bypass certain privilege checks by calling CREATE TABLE on a MyISAM table with modified (1) DATA DIRECTORY or (2) INDEX DIRECTORY arguments that are originally associated with pathnames without symlinks, and that can point to tables created at a future time at which a pathname is modified to contain a symlink to a subdirectory of the MySQL data home directory, related to incorrect calculation of the mysql_unpacked_real_data_home value. NOTE: this vulnerability exists because of a CVE-2009-4030 regression, which was not omitted in other packages and versions such as MySQL 5.0.95 in Red Hat Enterprise Linux 6.
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Analysis
by VulDB Data Team • 12/29/2024
This vulnerability in MySQL 5.0.88 represents a sophisticated privilege escalation issue that exploits a regression introduced in CVE-2009-4030, creating a pathway for local attackers to bypass critical access controls. The flaw manifests when users execute CREATE TABLE statements on MyISAM tables with modified DATA DIRECTORY or INDEX DIRECTORY arguments that originally reference pathnames without symbolic links. The vulnerability specifically arises from an incorrect calculation of the mysql_unpacked_real_data_home value, which occurs when these directory paths are manipulated to contain symlinks that point to subdirectories within the MySQL data home directory. This creates a temporal window where the system's privilege checking mechanism fails to properly validate directory access permissions, allowing attackers to potentially access restricted database objects or escalate their privileges within the MySQL environment.
The technical implementation of this vulnerability involves exploiting the timing gap between when directory paths are initially processed and when they are validated against the MySQL data home directory structure. When a CREATE TABLE statement is executed with modified directory arguments, the system calculates the mysql_unpacked_real_data_home value incorrectly, failing to properly resolve symbolic links that may have been modified after the initial path validation. This regression in the privilege checking mechanism means that even though the original pathnames do not contain symlinks, the subsequent modification of these paths to include symlinks can cause the system to incorrectly grant access to resources that should be restricted. The vulnerability specifically affects systems where the DATA DIRECTORY or INDEX DIRECTORY arguments are set to locations that can be manipulated to contain symlinks pointing to the MySQL data directory, creating a scenario where the privilege checks are bypassed due to improper path resolution logic.
The operational impact of this vulnerability extends beyond simple privilege escalation, potentially allowing attackers to access sensitive database information, modify table structures, or even execute unauthorized operations within the MySQL environment. Attackers can leverage this flaw to gain unauthorized access to database objects that should be protected by standard privilege controls, effectively circumventing the access restrictions designed to protect MySQL installations. The vulnerability is particularly concerning because it affects local users who already have access to the system, meaning that an attacker who has gained any level of access to the MySQL server can exploit this weakness to escalate their privileges further. This type of vulnerability aligns with CWE-264, which covers permissions, privileges, and access controls, and represents a specific implementation issue in the privilege validation logic that was introduced through a regression from a previous fix.
Mitigation strategies for this vulnerability require careful attention to path management and privilege validation within MySQL installations. System administrators should ensure that all MySQL installations are updated to versions that properly address this regression, particularly avoiding versions that contain the CVE-2009-4030 regression. The recommended approach includes implementing strict directory path validation that prevents the use of symbolic links in DATA DIRECTORY and INDEX DIRECTORY arguments, as well as ensuring that all pathnames used in these contexts are properly resolved before privilege checks are performed. Additionally, organizations should consider implementing monitoring solutions that can detect unauthorized modifications to directory structures that might be exploited for this vulnerability, as well as conducting regular security audits to verify that MySQL installations are not vulnerable to this type of privilege escalation attack. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the use of software vulnerabilities to bypass access controls and gain elevated system privileges.