CVE-2016-6624 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin involving improper enforcement of the IP-based authentication rules. When phpMyAdmin is used with IPv6 in a proxy server environment, and the proxy server is in the allowed range but the attacking computer is not allowed, this vulnerability can allow the attacking computer to connect despite the IP rules. All 4.6.x versions (prior to 4.6.4), 4.4.x versions (prior to 4.4.15.8), and 4.0.x versions (prior to 4.0.10.17) are affected.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability described in CVE-2016-6624 represents a critical authorization bypass flaw within phpMyAdmin that specifically impacts IPv6 network configurations in proxy server environments. This issue stems from the improper enforcement of IP-based authentication rules that should normally restrict access to authorized network ranges. The flaw manifests when phpMyAdmin operates in environments where IPv6 addresses are utilized alongside proxy servers, creating a scenario where network access controls can be circumvented through careful manipulation of the request routing process.
The technical implementation of this vulnerability occurs at the network layer validation mechanism within phpMyAdmin's authentication system. When a proxy server sits between clients and the phpMyAdmin instance, the application fails to properly validate the original client IP address when IPv6 addresses are involved. This happens because the application typically relies on the HTTP_X_FORWARDED_FOR header or similar proxy headers to determine client identity, but does not adequately verify that these headers contain legitimate information or that they originate from trusted proxy servers within the allowed IP ranges. The flaw allows an attacker positioned outside the authorized network range to potentially forge or manipulate these headers, thereby gaining unauthorized access to the database management interface.
The operational impact of this vulnerability is significant for organizations that rely on phpMyAdmin for database administration and that operate in complex network environments involving proxy servers and IPv6 addressing. Attackers can exploit this weakness to gain unauthorized access to database management interfaces without proper authentication, potentially leading to data breaches, unauthorized database modifications, or complete system compromise. The vulnerability affects multiple major release lines of phpMyAdmin, including the 4.6.x, 4.4.x, and 4.0.x series, making it a widespread concern for organizations maintaining legacy installations. The specific versions affected indicate that this flaw existed for several years without proper resolution, highlighting potential gaps in security testing and validation of network access controls in web applications.
This vulnerability aligns with CWE-284, which describes improper access control mechanisms, and can be mapped to ATT&CK technique T1190, representing exploitation of remote services through network-based attacks. The flaw demonstrates how proxy server configurations can create unexpected security boundaries when applications fail to properly validate network information. Organizations should immediately implement mitigations including updating to patched versions of phpMyAdmin, implementing additional network-level access controls, and configuring proper header validation within the application to ensure that proxy headers cannot be easily manipulated by unauthorized parties. The security community should also consider this vulnerability as an example of how modern web applications must account for complex network topologies and the potential for header-based spoofing attacks.
The root cause of this vulnerability highlights the importance of proper input validation and authentication flow in web applications, particularly those operating in complex network environments. The flaw demonstrates that applications must not only validate the immediate network context but also verify the integrity of forwarded headers and proxy information. This vulnerability serves as a reminder that network security controls should be implemented at multiple layers and that authentication systems must be robust enough to handle various deployment scenarios including those involving proxy servers and IPv6 addressing. Organizations should conduct comprehensive security testing of their network configurations and ensure that all authentication mechanisms properly validate the source of connection requests regardless of the underlying network protocol or proxy infrastructure in use.