CVE-2016-6620 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. Some data is passed to the PHP unserialize() function without verification that it's valid serialized data. The unserialization can result in code execution because of the interaction with object instantiation and autoloading. 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 identified as CVE-2016-6620 represents a critical security flaw in phpMyAdmin that stems from improper input validation during the deserialization process. This issue affects multiple version branches including 4.6.x prior to 4.6.4, 4.4.x prior to 4.4.15.8, and 4.0.x prior to 4.0.10.17, making it a widespread concern for database management interface deployments. The root cause lies in the application's failure to verify that serialized data conforms to expected formats before passing it to PHP's unserialize() function, creating a pathway for malicious code execution through object instantiation and autoloading mechanisms.
This vulnerability operates under the principle of insecure deserialization, where attacker-controlled data can be manipulated to trigger unintended object construction and method execution. When phpMyAdmin processes serialized data without proper validation, it becomes susceptible to object injection attacks that exploit PHP's autoloading capabilities. The interaction between the unserialize() function and PHP's automatic class loading mechanism allows attackers to instantiate objects with malicious payloads, potentially leading to remote code execution on the server. This flaw aligns with CWE-502 which specifically addresses deserialization of untrusted data, and represents a classic example of how improper input sanitization can create severe security implications in web applications.
The operational impact of this vulnerability extends beyond simple data corruption or access control breaches, as successful exploitation can result in complete system compromise. Attackers can leverage this vulnerability to execute arbitrary commands on the affected server, potentially gaining access to sensitive database information, modifying or deleting data, and establishing persistent backdoors. The attack surface is particularly concerning given that phpMyAdmin is widely deployed across organizations for database administration tasks, making it a prime target for exploitation. This vulnerability directly maps to ATT&CK technique T1059.007 for command and scripting interpreter, as well as T1566 for malicious file execution, since the exploitation involves executing code through the deserialization process.
Mitigation strategies for CVE-2016-6620 primarily focus on immediate patching and input validation improvements. Organizations should prioritize upgrading to patched versions of phpMyAdmin, specifically version 4.6.4, 4.4.15.8, or 4.0.10.17 respectively, to address the core deserialization flaw. Beyond patching, implementing strict input validation mechanisms that verify serialized data format before processing can provide additional defense-in-depth. Security measures should include disabling unnecessary serialization features, implementing proper access controls, and monitoring for suspicious deserialization activities. Network segmentation and application firewalls can also help limit the potential impact of successful exploitation attempts, while regular security audits should verify that no custom code introduces similar vulnerabilities into the system.