CVE-2015-4757 in MySQL Server
Summary
by MITRE
Unspecified vulnerability in Oracle MySQL Server 5.5.42 and earlier and 5.6.23 and earlier allows remote authenticated users to affect availability via unknown vectors related to Server : Optimizer.
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Analysis
by VulDB Data Team • 06/03/2022
The vulnerability identified as CVE-2015-4757 represents a critical availability issue within Oracle MySQL Server versions 5.5.42 and earlier, as well as 5.6.23 and earlier, affecting remote authenticated users who can exploit unknown vectors related to the Server Optimizer component. This flaw falls under the broader category of denial of service vulnerabilities that can compromise system availability and reliability. The Oracle MySQL Server optimizer is responsible for determining the most efficient execution plan for database queries, making it a critical component that directly impacts database performance and stability. When this component is compromised through the identified vulnerability, it can lead to complete system unavailability or significant degradation of service for legitimate users.
The technical nature of this vulnerability lies within the server optimizer's handling of specific query execution paths that can trigger unexpected behavior when processing certain database operations. The unspecified vector nature suggests that the flaw may manifest through multiple attack scenarios involving complex query structures, join operations, or optimization algorithms that are processed during query execution. This type of vulnerability typically exploits weaknesses in input validation, memory management, or control flow within the optimizer module. The fact that it requires authentication indicates that attackers must first establish valid credentials, but once authenticated, they can leverage this vulnerability to disrupt database operations. This characteristic places the vulnerability in the category of privilege escalation or lateral movement attacks within the context of database security, as it allows authenticated users to cause system-wide availability issues.
The operational impact of CVE-2015-4757 extends beyond simple service disruption to potentially compromise entire database infrastructure and business continuity operations. When exploited, this vulnerability can cause the MySQL server process to crash, hang, or become unresponsive, effectively preventing legitimate database access for all users. Organizations relying on MySQL databases for critical applications face significant risk of data unavailability, transaction failures, and potential revenue loss during exploitation periods. The vulnerability's impact is particularly severe in high-availability environments where database uptime is critical, as it can cause cascading failures throughout dependent systems that rely on database services. Additionally, the remote nature of the attack means that unauthorized parties can exploit this vulnerability from external networks, potentially leading to widespread service disruption across multiple database instances.
Mitigation strategies for CVE-2015-4757 should prioritize immediate patching of affected MySQL server versions to the latest available releases that contain fixes for the optimizer-related vulnerability. Organizations should implement network segmentation and access controls to limit the number of authenticated users who can reach database servers, reducing the attack surface for exploitation. Regular monitoring of database server processes and performance metrics can help identify potential exploitation attempts through unusual resource consumption patterns or process behavior. Security teams should also consider implementing database activity monitoring solutions that can detect anomalous query patterns or execution paths that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and CWE-400 for uncontrolled resource consumption, highlighting the importance of proper resource management and input validation in database server implementations. Organizations should also conduct regular vulnerability assessments and penetration testing to identify similar issues in their database environments and ensure that all security patches are properly applied across their infrastructure.
The broader implications of this vulnerability demonstrate the critical importance of maintaining up-to-date database software and implementing robust security monitoring practices. Database administrators should establish regular patch management procedures that include thorough testing of security updates before deployment to prevent service disruptions. The vulnerability also underscores the need for comprehensive security awareness training for database administrators and developers to recognize potential security flaws in query optimization and execution processes. Organizations should maintain detailed incident response plans that specifically address database availability issues, including procedures for rapid patch deployment, system recovery, and forensic analysis when such vulnerabilities are exploited. This case serves as a reminder that even authenticated access can be leveraged to cause significant availability impacts, emphasizing the importance of principle of least privilege and comprehensive access control measures in database security architectures.