CVE-2012-0830 in PHP
Summary
by MITRE
The php_register_variable_ex function in php_variables.c in PHP 5.3.9 allows remote attackers to execute arbitrary code via a request containing a large number of variables, related to improper handling of array variables. NOTE: this vulnerability exists because of an incorrect fix for CVE-2011-4885.
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Analysis
by VulDB Data Team • 12/16/2024
The vulnerability identified as CVE-2012-0830 represents a critical remote code execution flaw in PHP versions up to 5.3.9, specifically within the php_register_variable_ex function located in php_variables.c. This vulnerability stems from improper handling of array variables during HTTP request processing, creating a pathway for attackers to execute arbitrary code on affected systems. The flaw manifests when a malicious request contains an excessive number of variables, triggering a buffer overflow condition that can be exploited to gain unauthorized system access.
The technical root cause of this vulnerability lies in the inadequate memory management and input validation mechanisms within PHP's variable registration system. When processing HTTP requests with numerous variables, the php_register_variable_ex function fails to properly validate the number of variables being processed, leading to memory corruption that can be leveraged by attackers. This improper handling creates a condition where the application's memory space becomes corrupted, potentially allowing an attacker to overwrite critical memory locations and execute malicious code. The vulnerability is particularly dangerous because it can be triggered through normal HTTP request processing without requiring special privileges or authentication.
This vulnerability directly relates to CWE-121, which describes stack-based buffer overflow conditions, and aligns with ATT&CK technique T1059.007 for command and script injection. The operational impact of CVE-2012-0830 is severe as it allows remote attackers to execute arbitrary commands on affected web servers, potentially leading to complete system compromise. Attackers can leverage this vulnerability to establish persistent backdoors, exfiltrate sensitive data, or use the compromised server as a launch point for further attacks within the network infrastructure. The vulnerability's exploitation is particularly concerning because it can be triggered through standard web application interfaces, making it accessible to attackers with minimal technical expertise.
The vulnerability exists due to an incorrect fix for CVE-2011-4885, which demonstrates the complexity of vulnerability remediation and the potential for introducing new issues during patch development. Organizations running affected PHP versions face significant risk as this vulnerability can be exploited through various attack vectors including web application requests, file uploads, or any method that triggers HTTP variable processing. The remediation strategy requires immediate patching to PHP version 5.3.10 or later, which properly addresses the memory handling issues in the variable registration process. Additionally, implementing input validation controls, rate limiting for HTTP requests, and monitoring for unusual variable counts in web requests can provide additional layers of defense against exploitation attempts.