CVE-2017-3638 in MySQL Server
Summary
by MITRE
Vulnerability in the MySQL Server component of Oracle MySQL (subcomponent: Server: Optimizer). Supported versions that are affected are 5.7.18 and earlier. Easily exploitable vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.0 Base Score 4.9 (Availability impacts). CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 01/04/2021
The vulnerability identified as CVE-2017-3638 resides within the MySQL Server component, specifically within the Server: Optimizer subcomponent, affecting MySQL versions 5.7.18 and earlier. This flaw represents a significant security concern as it operates within the core database engine that processes query optimization, making it a critical point of failure for database operations. The vulnerability's classification as easily exploitable indicates that attackers with high privileges and network access can leverage this weakness without requiring extensive technical expertise or resources. The attack vector through multiple protocols suggests that the flaw can be exploited across various network communication channels, increasing its potential impact and attack surface.
The technical nature of this vulnerability manifests as a flaw in the query optimizer's handling of specific database operations, leading to a denial of service condition that can cause complete system crashes or frequent restarts. This behavior aligns with the Common Weakness Enumeration CWE-121, which categorizes buffer overflow conditions that can lead to system instability and availability disruption. The vulnerability's design allows attackers with elevated privileges to craft malicious queries or database operations that trigger memory corruption or resource exhaustion within the optimizer module. The complete denial of service capability means that legitimate database operations cannot proceed, effectively rendering the MySQL server unavailable to authorized users while maintaining the system's operational state.
From an operational impact perspective, this vulnerability creates a substantial risk for database environments where MySQL serves as a critical backend service for applications and business processes. The availability impact score of 4.9 on the CVSS 3.0 scale indicates a moderate to high severity threat that can disrupt business operations and compromise service level agreements. The fact that this vulnerability requires only high privileged access rather than administrative credentials makes it particularly dangerous as it can be exploited by insiders or compromised accounts with elevated database permissions. The repeated crash potential suggests that even a single successful attack can cause sustained disruption, requiring system administrators to perform manual intervention and potentially leading to extended downtime periods. This type of vulnerability directly impacts the availability aspect of the CIA triad, potentially causing cascading failures in applications that depend on the database for their operations.
The mitigation strategy for CVE-2017-3638 primarily involves upgrading to MySQL versions that have addressed this specific optimizer flaw, which would typically be versions beyond 5.7.18. Organizations should also implement network segmentation and access controls to limit the potential attack surface, ensuring that only authorized personnel have high privileged access to database systems. Monitoring and logging mechanisms should be enhanced to detect unusual query patterns or system behavior that might indicate exploitation attempts. The vulnerability's classification under the ATT&CK framework would fall under the T1499 category for network denial of service, with potential lateral movement implications if attackers can use the disruption to gain additional access. Database administrators should also consider implementing query execution limits and resource controls to prevent exploitation attempts from causing complete system failure. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities within database environments, while maintaining updated security patches across all database components to prevent similar issues from arising in the future.