CVE-2007-1484 in PHP
Summary
by MITRE
The array_user_key_compare function in PHP 4.4.6 and earlier, and 5.x up to 5.2.1, makes erroneous calls to zval_dtor, which triggers memory corruption and allows local users to bypass safe_mode and execute arbitrary code via a certain unset operation after array_user_key_compare has been called.
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Analysis
by VulDB Data Team • 01/01/2025
The vulnerability identified as CVE-2007-1484 represents a critical memory corruption flaw within the PHP scripting language that affects versions 4.4.6 and earlier, as well as PHP 5.x versions up to 5.2.1. This issue stems from improper handling of memory management within the array_user_key_compare function, which is a core component responsible for comparing array keys during user-defined array operations. The flaw manifests when the function makes erroneous calls to zval_dtor, a destructor function that manages the cleanup of zval structures used internally by PHP's Zend Engine. This improper memory handling creates a condition where memory corruption occurs, potentially leading to arbitrary code execution.
The technical exploitation of this vulnerability occurs through a specific sequence involving unset operations that follow calls to array_user_key_compare. When PHP processes certain array operations that trigger this function, the erroneous zval_dtor calls result in memory being freed or overwritten incorrectly. This memory corruption creates a scenario where local attackers can manipulate the execution flow of the PHP interpreter. The vulnerability particularly impacts safe_mode protection mechanisms, which are designed to restrict file system access and prevent unauthorized operations. By exploiting the memory corruption, attackers can bypass these security controls and execute malicious code with the privileges of the web server process. The flaw demonstrates a classic buffer overflow or use-after-free condition that can be leveraged for privilege escalation and arbitrary code execution.
The operational impact of CVE-2007-1484 extends beyond simple code execution, as it fundamentally undermines the security model of PHP applications running on vulnerable systems. Since the vulnerability allows bypassing safe_mode restrictions, it provides attackers with access to file system operations that should normally be restricted, potentially enabling them to read sensitive files, modify application data, or even install backdoors on the affected servers. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a significant concern for web applications that rely on PHP for dynamic content generation. The attack vector requires local access to the system, but the potential for privilege escalation and data compromise makes this vulnerability particularly dangerous in shared hosting environments or when PHP applications handle sensitive user data.
Organizations affected by this vulnerability should immediately implement mitigations including updating to patched versions of PHP, specifically versions 4.4.7 and 5.2.2 or later, where the memory management issues have been resolved. System administrators should also consider implementing additional security measures such as disabling potentially dangerous functions, restricting file permissions, and monitoring for unusual system activity that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of keeping PHP installations updated and maintaining proper security configurations. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and execution of arbitrary code, with potential for lateral movement if exploited in web applications that have access to sensitive system resources. Regular security audits and vulnerability assessments should include checks for outdated PHP versions to prevent exploitation of similar memory corruption vulnerabilities that may exist in other components of the web application stack.