CVE-2016-6606 in phpMyAdmin
Summary
by MITRE
An issue was discovered in cookie encryption in phpMyAdmin. The decryption of the username/password is vulnerable to a padding oracle attack. This can allow an attacker who has access to a user's browser cookie file to decrypt the username and password. Furthermore, the same initialization vector (IV) is used to hash the username and password stored in the phpMyAdmin cookie. If a user has the same password as their username, an attacker who examines the browser cookie can see that they are the same - but the attacker can not directly decode these values from the cookie as it is still hashed. 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-2016-6606 represents a critical weakness in phpMyAdmin's cookie encryption implementation that exposes user authentication credentials to sophisticated attack vectors. This issue specifically targets the encryption mechanisms used to store username and password information within browser cookies, creating a pathway for unauthorized access to database authentication details. The vulnerability affects multiple major release branches of phpMyAdmin, including versions 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, indicating a widespread impact across the software's user base.
The core technical flaw lies in the implementation of the padding oracle attack vulnerability within the decryption process. This type of attack exploits the way the system responds to invalid padding in encrypted data to gradually reveal the original plaintext content. In the context of phpMyAdmin, an attacker who gains access to a user's browser cookie file can leverage this vulnerability to decrypt the stored username and password information. The attack methodology relies on the predictable behavior of the decryption function when it encounters malformed padding, allowing an attacker to systematically determine the correct decryption key through multiple trial and error attempts. This weakness directly aligns with CWE-209, which addresses the exposure of sensitive information through error messages, and represents a significant deviation from secure cryptographic practices.
The operational impact of this vulnerability extends beyond simple credential theft, as it creates multiple attack vectors for malicious actors seeking unauthorized database access. The use of the same initialization vector (IV) for hashing both username and password values introduces an additional layer of risk, as it allows attackers to correlate and analyze patterns within the encrypted cookie data. While the actual values remain hashed, the identical IV usage creates detectable patterns that can reveal when a user's username and password are identical, providing attackers with additional intelligence about potential target accounts. This vulnerability particularly affects environments where phpMyAdmin is used for database administration, as successful exploitation would grant attackers direct access to database servers and potentially sensitive information stored within them.
The security implications of this vulnerability are compounded by the fact that it operates at the cookie level, making it accessible through relatively simple means such as browser cookie inspection or session hijacking techniques. Attackers can exploit this weakness without requiring elevated privileges or complex infrastructure, as they only need to obtain a valid user session cookie from a compromised browser. The vulnerability also relates to ATT&CK technique T1566, which covers credential access through social engineering or session manipulation. Organizations using affected phpMyAdmin versions face significant risk of unauthorized database access, data breaches, and potential lateral movement within their network infrastructure. The attack surface is further expanded when considering that phpMyAdmin is commonly used in web hosting environments, making it a prime target for attackers seeking to compromise database servers and associated applications.
The recommended mitigations for this vulnerability include immediate upgrading to patched versions of phpMyAdmin, specifically versions 4.6.4, 4.4.15.8, and 4.0.10.17 respectively. Administrators should also implement additional security measures such as enforcing secure cookie attributes including HttpOnly and Secure flags, implementing proper session management protocols, and monitoring for unauthorized access attempts. Organizations should consider implementing network-based intrusion detection systems to monitor for suspicious cookie access patterns and conduct regular security audits of their phpMyAdmin installations. The vulnerability underscores the importance of proper cryptographic implementation and highlights the need for regular security updates and patch management processes. Additionally, organizations should consider alternative authentication mechanisms for database access and implement multi-factor authentication where possible to reduce the impact of credential compromise.