CVE-2016-9847 in phpMyAdmin
Summary
by MITRE
An issue was discovered in phpMyAdmin. When the user does not specify a blowfish_secret key for encrypting cookies, phpMyAdmin generates one at runtime. A vulnerability was reported where the way this value is created uses a weak algorithm. This could allow an attacker to determine the user's blowfish_secret and potentially decrypt their cookies. 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 • 06/25/2019
The vulnerability identified as CVE-2016-9847 represents a critical cryptographic weakness in phpMyAdmin's cookie encryption mechanism that fundamentally undermines user session security. This issue manifests when administrators fail to explicitly configure the blowfish_secret parameter in their phpMyAdmin configuration, prompting the application to automatically generate this crucial encryption key at runtime. The flaw lies in the algorithmic approach used for this automatic generation, which employs insufficient entropy and predictable patterns that make the generated secret susceptible to cryptographic analysis and reverse engineering attempts.
The technical implementation of this vulnerability stems from phpMyAdmin's reliance on weak random number generation during the automatic blowfish_secret creation process. When no explicit secret is provided, the application's runtime generation mechanism produces keys that lack adequate cryptographic strength, typically utilizing predictable sequences or insufficient randomness sources. This weakness directly violates established cryptographic best practices and security standards such as those outlined in the National Institute of Standards and Technology's Special Publication 800-90A, which specifies requirements for cryptographic random number generators. The vulnerability creates a path for attackers to perform brute force or statistical analysis attacks against the generated keys, potentially enabling session hijacking and unauthorized access to database management interfaces.
The operational impact of this vulnerability extends beyond simple session theft, as it provides attackers with the capability to decrypt user authentication cookies and gain unauthorized access to database management sessions. This weakness affects multiple major release branches of phpMyAdmin, specifically versions 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, indicating a widespread exposure across the application's user base. The implications align with attack patterns documented in the MITRE ATT&CK framework under the T1566 technique for credential access through session hijacking and T1078 for valid accounts usage. Organizations using affected versions face significant risk of unauthorized database access, potential data breaches, and escalation of privileges within their database environments.
Mitigation strategies for CVE-2016-9847 require immediate implementation of explicit blowfish_secret configuration in phpMyAdmin's configuration files, ensuring that administrators generate and deploy cryptographically strong random strings for this parameter. The recommended approach involves generating a sufficiently long random string using secure random number generators and storing it in the phpMyAdmin configuration, typically within the config.inc.php file. Additionally, system administrators should upgrade to patched versions of phpMyAdmin that address the weak random number generation algorithm, specifically versions 4.6.5, 4.4.15.9, and 4.0.10.18 or later. Security monitoring should include verification of blowfish_secret configuration presence and strength, while network segmentation and access controls should be implemented to limit exposure of phpMyAdmin interfaces to trusted users only. This vulnerability underscores the critical importance of proper cryptographic key management practices and the necessity of explicit security configuration in web applications, as outlined in the CWE database under category CWE-327 for use of weak cryptography.