CVE-2016-9860 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. An unauthenticated user can execute a denial of service attack when phpMyAdmin is running with $cfg['AllowArbitraryServer']=true. All 4.6.x versions (prior to 4.6.5), 4.4.x versions (prior to 4.4.15.9), and 4.0.x versions (prior to 4.0.10.18) are affected.
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Analysis
by VulDB Data Team • 06/23/2019
The vulnerability identified as CVE-2016-9860 represents a critical denial of service weakness in phpMyAdmin, a widely used web-based database management tool that allows administrators and users to interact with mysql and mariadb databases through a graphical interface. This flaw specifically targets configurations where the $cfg['AllowArbitraryServer'] setting is enabled, which permits users to connect to any database server specified by the user rather than being restricted to predefined connections. The vulnerability exists in multiple version streams of phpMyAdmin including the 4.6.x series prior to 4.6.5, 4.4.x series prior to 4.4.15.9, and 4.0.x series prior to 4.0.10.18, indicating a prolonged period of exposure across different release lines. The security implications are particularly concerning given that phpMyAdmin is deployed in numerous production environments where it serves as a critical interface for database administration tasks.
The technical mechanism behind this vulnerability involves an insufficient input validation and resource handling issue that occurs when arbitrary server connections are permitted. When an unauthenticated attacker accesses the phpMyAdmin interface with the AllowArbitraryServer configuration enabled, they can craft malicious requests that cause the application to consume excessive system resources or enter an infinite loop. This typically manifests through improper handling of connection parameters or server specifications that are passed to the underlying database connection mechanisms. The flaw allows attackers to exploit the application's inability to properly validate or limit the resources consumed during the connection process, leading to a condition where legitimate users cannot access the service due to resource exhaustion. This represents a classic denial of service scenario where the attacker's actions directly impact the availability of the service rather than compromising confidentiality or integrity.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire database environments. Organizations running vulnerable versions of phpMyAdmin with arbitrary server connections enabled face the risk of their database management interfaces becoming unavailable to authorized users, which can severely impact database administration tasks and potentially lead to extended downtime during critical maintenance periods. The vulnerability is particularly dangerous in shared hosting environments or multi-tenant deployments where multiple users access the same phpMyAdmin instance, as a single malicious actor can affect all users of the service. Additionally, the fact that this vulnerability affects multiple version streams indicates that many organizations may have been unknowingly exposed for extended periods, potentially allowing attackers to establish persistent access patterns or conduct reconnaissance activities before exploiting the denial of service capabilities.
The weakness aligns with CWE-400, which catalogs weaknesses related to resource management issues including denial of service vulnerabilities, and may also relate to CWE-20, which covers input validation problems that can lead to resource exhaustion. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004, which involves network denial of service attacks targeting availability, and potentially T1566.002 for social engineering techniques that could be used to gain initial access to systems running vulnerable phpMyAdmin configurations. Organizations should immediately implement mitigation strategies including disabling the AllowArbitraryServer configuration when not strictly necessary, applying the relevant security patches to upgrade to versions 4.6.5, 4.4.15.9, or 4.0.10.18 respectively, and implementing network-level controls to monitor for suspicious connection patterns. Additional protective measures include restricting access to phpMyAdmin through network firewalls, implementing rate limiting on connection attempts, and conducting regular security assessments to identify other potential configuration weaknesses that could be exploited in similar manners.