CVE-2016-9866 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. When the arg_separator is different from its default & value, the CSRF token was not properly stripped from the return URL of the preference import action. 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 • 10/05/2022
The vulnerability identified as CVE-2016-9866 represents a critical security flaw in phpMyAdmin that undermines the application's cross-site request forgery protection mechanisms. This issue specifically affects versions of phpMyAdmin that have been configured with a custom arg_separator parameter value, which deviates from the default ampersand character. The flaw resides in how the application handles URL parameter parsing during preference import operations, creating a pathway for malicious actors to exploit the weakened CSRF token validation process.
The technical implementation of this vulnerability stems from phpMyAdmin's improper handling of URL parameter separation when the arg_separator configuration differs from the standard ampersand character. When users attempt to import preferences through the web interface, the application fails to correctly strip or sanitize the CSRF token from the return URL if the arg_separator has been modified from its default value. This creates a scenario where the token validation mechanism becomes ineffective, as the token remains embedded in the redirect URL and can be manipulated by attackers.
The operational impact of this vulnerability extends beyond simple CSRF attacks, as it can enable attackers to perform unauthorized actions within the phpMyAdmin interface on behalf of authenticated users. The flaw affects multiple version streams including 4.6.x prior to 4.6.5, 4.4.x prior to 4.4.15.9, and 4.0.x prior to 4.0.10.18, representing a substantial portion of the phpMyAdmin user base during the affected time period. Attackers could potentially leverage this vulnerability to execute commands, modify database configurations, or gain unauthorized access to sensitive database information through carefully crafted malicious requests.
From a cybersecurity perspective, this vulnerability aligns with CWE-352, which specifically addresses Cross-Site Request Forgery issues, and demonstrates the critical importance of proper input validation and parameter handling in web applications. The flaw also connects to ATT&CK technique T1078 which covers valid accounts and privilege escalation through application-level attacks. Organizations using phpMyAdmin with custom arg_separator configurations were particularly vulnerable, as the default security mechanisms failed to properly validate or sanitize URL parameters during preference import operations. The vulnerability highlights the necessity of maintaining default security configurations and the potential risks associated with customizing web application parameters without proper security testing.
The recommended mitigation strategy involves upgrading to patched versions of phpMyAdmin, specifically versions 4.6.5, 4.4.15.9, or 4.0.10.18 respectively, which contain the necessary fixes for proper CSRF token handling. Additionally, administrators should review their phpMyAdmin configurations to ensure that arg_separator parameters are not being modified unless absolutely necessary, as this vulnerability demonstrates how seemingly minor configuration changes can create significant security risks. Security monitoring should include detection of unauthorized preference import activities and unusual URL parameter patterns that might indicate exploitation attempts.