CVE-2007-1401 in PHP
Summary
by MITRE
Buffer overflow in the crack extension (CrackLib), as bundled with PHP 4.4.6 and other versions before 5.0.0, might allow local users to gain privileges via a long argument to the crack_opendict function.
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Analysis
by VulDB Data Team • 08/26/2024
The vulnerability identified as CVE-2007-1401 represents a critical buffer overflow condition within the crack extension of PHP versions prior to 5.0.0. This flaw specifically affects the crack_opendict function which is part of the CrackLib library integration within PHP's security framework. The issue stems from inadequate input validation and memory management within the extension, creating a scenario where malicious input can overwrite adjacent memory locations. The vulnerability exists in PHP versions 4.4.6 and earlier, as well as other versions before the 5.0.0 release, making it a widespread concern across multiple PHP iterations. The crack extension is designed to provide password strength checking capabilities by utilizing CrackLib, a library for checking password strength against common dictionary words and patterns. When the crack_opendict function processes user-supplied arguments without proper bounds checking, it creates an exploitable condition that can be leveraged by local attackers to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability involves the improper handling of string arguments passed to the crack_opendict function. When a maliciously long argument is provided, the function fails to validate the input length against the allocated buffer size, leading to memory corruption. This buffer overflow condition allows attackers to overwrite critical memory locations including return addresses, function pointers, or other control data structures. The vulnerability operates at the kernel level within the PHP interpreter's memory management system, where the stack-based buffer overflow can be exploited to redirect program execution flow. The flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of insufficient bounds checking in software development. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the PHP process, potentially leading to full system compromise when PHP is running with elevated permissions.
The operational impact of CVE-2007-1401 extends beyond simple privilege escalation, as it can be exploited in various attack scenarios including local privilege escalation, denial of service conditions, and potentially remote code execution depending on the system configuration. Systems running vulnerable PHP versions with the crack extension enabled are at risk, particularly when PHP is configured to accept user input through web interfaces or command-line arguments. The vulnerability is particularly concerning because it affects the core PHP functionality and can be exploited even in environments where PHP is not directly exposed to external networks. Organizations using PHP-based web applications that incorporate password validation features are especially vulnerable, as these applications may be running with elevated privileges during password checking operations. The exploitability of this vulnerability is enhanced by the fact that it requires no special network access, making it a local privilege escalation vector that can be leveraged by attackers who already have access to the system.
Mitigation strategies for CVE-2007-1401 must address both immediate remediation and long-term architectural improvements. The primary recommendation is to upgrade to PHP 5.0.0 or later versions where this vulnerability has been resolved through improved input validation and memory management. Organizations should also consider disabling the crack extension if password strength checking is not critical to their applications, as this eliminates the attack surface entirely. System administrators should implement proper access controls and privilege separation to minimize the impact of potential exploitation, ensuring that PHP processes run with minimal required privileges. Additionally, implementing input validation at multiple layers including web application firewalls and application-level checks can provide defense-in-depth measures. The vulnerability demonstrates the importance of following secure coding practices and adhering to industry standards such as those outlined in the OWASP Top Ten and NIST guidelines for secure software development. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in other PHP extensions or components that may be vulnerable to similar buffer overflow conditions.