CVE-2014-9906 in DBD::mysql
Summary
by MITRE
Use-after-free vulnerability in DBD::mysql before 4.029 allows attackers to cause a denial of service (program crash) or possibly execute arbitrary code via vectors related to a lost server connection.
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Analysis
by VulDB Data Team • 09/14/2022
The CVE-2014-9906 vulnerability represents a critical use-after-free flaw in the DBD::mysql Perl database driver library, which affects versions prior to 4.029. This vulnerability resides within the database connectivity layer that applications use to communicate with mysql database servers, making it particularly dangerous in environments where Perl applications interact with database systems. The flaw manifests when the driver encounters a lost server connection scenario, creating a condition where memory that has been freed is subsequently accessed, leading to unpredictable behavior. Such vulnerabilities are classified under CWE-416, which specifically addresses use-after-free conditions, and they represent a fundamental memory safety issue that can be exploited by malicious actors to compromise system integrity.
The technical exploitation of this vulnerability occurs when a Perl application using DBD::mysql experiences a network interruption or server disconnection during database operations. During the cleanup process following such a connection loss, the driver fails to properly manage memory references, causing freed memory blocks to be accessed again. This memory corruption can result in program crashes that manifest as denial of service conditions, or in more severe cases, arbitrary code execution if attackers can control the memory layout and inject malicious payloads. The vulnerability is particularly insidious because it leverages legitimate database connection handling routines, making it difficult to distinguish between normal application behavior and malicious exploitation attempts.
From an operational perspective, this vulnerability impacts any Perl application that relies on DBD::mysql for database connectivity, particularly web applications, enterprise systems, and automated scripts that perform database operations. The potential for denial of service means that attackers can disrupt critical business operations by causing application crashes, while the arbitrary code execution capability allows for complete system compromise. This vulnerability aligns with ATT&CK technique T1059.007 for command and script injection, as successful exploitation could enable attackers to execute malicious code within the application environment. Organizations running affected versions face significant risk, especially in environments where database connectivity is frequent and where applications may be exposed to untrusted network conditions or malicious input.
Mitigation strategies for CVE-2014-9906 primarily involve upgrading to DBD::mysql version 4.029 or later, which contains the necessary memory management fixes to prevent the use-after-free condition. System administrators should prioritize patching affected systems, particularly those handling sensitive data or serving critical business functions. Additional protective measures include implementing network segmentation to reduce exposure to potentially malicious connections, monitoring for unusual connection patterns that might indicate exploitation attempts, and ensuring proper input validation to prevent attackers from manipulating database connection states. Organizations should also consider implementing intrusion detection systems that can identify patterns associated with memory corruption exploits and maintain regular security assessments to identify other potential vulnerabilities in their database connectivity stacks.