CVE-2007-4659 in PHP
Summary
by MITRE
The zend_alter_ini_entry function in PHP before 5.2.4 does not properly handle an interruption to the flow of execution triggered by a memory_limit violation, which has unknown impact and attack vectors.
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Analysis
by VulDB Data Team • 07/25/2019
The vulnerability identified as CVE-2007-4659 resides within the zend_alter_ini_entry function of PHP versions prior to 5.2.4, representing a critical flaw in the PHP interpreter's configuration management system. This issue manifests when the execution flow is abruptly interrupted due to a memory_limit violation, creating an unpredictable state within the PHP runtime environment. The vulnerability classifies under CWE-252, which deals with insufficient control flow management, specifically focusing on scenarios where program execution is disrupted without proper handling mechanisms. The memory_limit violation occurs when PHP attempts to allocate more memory than permitted by the configured limit, triggering a fatal error that should normally terminate execution gracefully.
The technical exploitation of this vulnerability stems from PHP's improper handling of memory allocation failures during runtime configuration changes. When zend_alter_ini_entry attempts to modify configuration parameters while memory constraints are being enforced, the function fails to maintain proper state management during the interruption. This creates a potential for undefined behavior that could lead to memory corruption or execution flow manipulation. The attack surface becomes particularly dangerous when considering that configuration changes often occur during script execution, making the timing of memory_limit violations unpredictable and potentially exploitable. The vulnerability impacts the fundamental execution integrity of PHP applications, as the normal flow of program execution becomes compromised during critical configuration management operations.
The operational impact of this vulnerability extends beyond simple execution failures, potentially allowing attackers to manipulate the PHP runtime environment in ways that could lead to more severe consequences. Although the exact attack vectors remain unspecified, the nature of the flaw suggests potential for privilege escalation or code execution within the context of the web server process. The memory_limit violation scenario typically occurs during resource-intensive operations such as large file processing, recursive operations, or memory allocation attempts that exceed configured boundaries. This creates a window of opportunity for exploitation, particularly in environments where PHP applications handle untrusted input or perform complex operations that may trigger memory constraints during configuration modifications.
Mitigation strategies for CVE-2007-4659 focus primarily on upgrading to PHP version 5.2.4 or later, where the zend_alter_ini_entry function has been properly patched to handle execution interruptions during memory limit violations. System administrators should implement comprehensive monitoring of PHP memory usage patterns to identify potential triggers for this vulnerability, particularly in applications that perform frequent configuration changes or handle large data sets. The ATT&CK framework categorizes this vulnerability under T1059.007 for PHP-based execution and T1068 for local privilege escalation, highlighting the need for proper access controls and execution environment hardening. Organizations should also consider implementing PHP-specific security modules and runtime protections that can detect and prevent abnormal execution patterns during memory constraint events, as the vulnerability represents a fundamental flaw in how PHP manages its internal state during critical error conditions.