CVE-2011-3189 in PHP
Summary
by MITRE
The crypt function in PHP 5.3.7, when the MD5 hash type is used, returns the value of the salt argument instead of the hashed string, which might allow remote attackers to bypass authentication via an arbitrary password, a different vulnerability than CVE-2011-2483.
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Analysis
by VulDB Data Team • 01/06/2025
The vulnerability described in CVE-2011-3189 represents a critical flaw in PHP's cryptographic implementation that directly impacts authentication security mechanisms. This issue specifically affects PHP version 5.3.7 and occurs within the crypt function when utilizing MD5 hash types. The flaw manifests as a return value manipulation where instead of generating and returning the properly hashed password string, the function returns the original salt argument value. This behavior fundamentally undermines the cryptographic integrity of password verification processes, creating a significant security gap that malicious actors can exploit to bypass authentication systems. The vulnerability operates at the core of PHP's password hashing infrastructure, making it particularly dangerous as it affects the fundamental building blocks of user authentication across numerous web applications.
From a technical perspective, the flaw constitutes a classic implementation error in cryptographic functions where the return value logic is inverted or incorrectly handled. The crypt function in PHP is designed to take a password and salt as inputs and produce a cryptographic hash that can be verified later against user credentials. When the MD5 hash type is specified, the function should process the input through the MD5 algorithm and return the resulting hash value. However, in this specific vulnerability, the function incorrectly returns the salt parameter instead of the computed hash, effectively rendering the entire password verification process useless. This behavior creates a scenario where any password input will be validated as long as the salt matches, regardless of the actual password provided, making it trivial for attackers to gain unauthorized access.
The operational impact of CVE-2011-3189 extends far beyond simple authentication bypass, as it affects the fundamental security model of applications relying on PHP's crypt function for password verification. Attackers can exploit this vulnerability by simply providing any password along with a matching salt value, effectively allowing them to log into any account without knowing the actual password. This creates a massive security risk for web applications including content management systems, user authentication portals, and any platform that depends on PHP's built-in cryptographic functions for securing user credentials. The vulnerability's impact is amplified because it affects a core PHP function used by thousands of applications worldwide, making it a prime target for exploitation across various web platforms and services.
Security professionals should recognize this vulnerability as a direct violation of cryptographic best practices and proper function implementation standards. The flaw aligns with CWE-254, which addresses security weaknesses in cryptographic implementations, and demonstrates poor input validation and output handling in security-critical functions. From an attack perspective, this vulnerability maps directly to ATT&CK technique T1110.003, which covers credential dumping and password cracking, as it essentially allows for the bypass of authentication mechanisms without requiring traditional password cracking approaches. Organizations should immediately implement mitigation strategies including updating to PHP versions that resolve this issue, implementing additional authentication layers, and conducting comprehensive security audits of applications that rely on the affected crypt function. The vulnerability also highlights the importance of thorough testing of cryptographic implementations and the necessity of validating return values in security-critical functions to prevent such fundamental logic errors from compromising system integrity.