CVE-2016-1251 in DBD-mysql
Summary
by MITRE
There is a vulnerability of type use-after-free affecting DBD::mysql (aka DBD-mysql or the Database Interface (DBI) MySQL driver for Perl) 3.x and 4.x before 4.041 when used with mysql_server_prepare=1.
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Analysis
by VulDB Data Team • 10/04/2022
The vulnerability identified as CVE-2016-1251 represents a critical use-after-free condition within the DBD::mysql Perl module, which serves as the Database Interface (DBI) MySQL driver for Perl applications. This flaw specifically manifests when the mysql_server_prepare=1 parameter is enabled, creating a scenario where memory allocated to database connection handles becomes prematurely freed while still being referenced by active operations. The vulnerability affects versions 3.x and 4.x of the DBD::mysql module prior to the 4.041 release, exposing a significant security risk to applications that rely on this database interface for MySQL connectivity.
The technical exploitation of this use-after-free vulnerability occurs through the improper management of memory resources during prepared statement execution. When mysql_server_prepare=1 is enabled, the driver delegates prepared statement handling to the MySQL server itself, which requires the driver to maintain internal references to statement handles and associated memory structures. The flaw arises when these memory regions are freed during connection cleanup or statement deallocation processes while still being accessed by concurrent operations, leading to potential memory corruption and arbitrary code execution. This type of vulnerability falls under CWE-416, which specifically addresses the use of freed memory, and represents a classic example of memory safety issues in C-based extensions that Perl modules often rely upon for database connectivity.
The operational impact of CVE-2016-1251 extends beyond simple memory corruption, as it creates opportunities for remote code execution and denial of service attacks against systems running vulnerable Perl applications. Attackers can exploit this vulnerability by crafting specific database queries that trigger the memory management race condition, potentially allowing them to execute arbitrary code with the privileges of the affected application process. The vulnerability is particularly concerning in web applications and server environments where Perl-based database interfaces are commonly used, as these systems often handle sensitive data and may be exposed to untrusted input from network clients. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to establish persistent access through command execution capabilities.
Mitigation strategies for CVE-2016-1251 primarily focus on updating to the patched version of DBD::mysql, specifically version 4.041 or later, which addresses the memory management issues in the prepared statement handling code. System administrators should also consider disabling mysql_server_prepare=1 parameter in application configurations where possible, as this parameter is not essential for all use cases and removes the attack surface for this vulnerability. Additionally, implementing network segmentation and access controls around database systems can limit the potential impact of successful exploitation attempts. Organizations should conduct thorough vulnerability assessments to identify all systems using affected versions of the DBD::mysql module and ensure proper patch management procedures are in place to prevent similar vulnerabilities from affecting their infrastructure. The fix implemented in version 4.041 includes proper reference counting mechanisms and memory deallocation sequences that prevent the premature freeing of resources while maintaining the functionality of server-side prepared statements.