CVE-2014-4721 in PHP
Summary
by MITRE • 01/25/2023
The phpinfo implementation in ext/standard/info.c in PHP before 5.4.30 and 5.5.x before 5.5.14 does not ensure use of the string data type for the PHP_AUTH_PW, PHP_AUTH_TYPE, PHP_AUTH_USER, and PHP_SELF variables, which might allow context-dependent attackers to obtain sensitive information from process memory by using the integer data type with crafted values, related to a "type confusion" vulnerability, as demonstrated by reading a private SSL key in an Apache HTTP Server web-hosting environment with mod_ssl and a PHP 5.3.x mod_php.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability described in CVE-2014-4721 represents a critical type confusion issue within PHP's phpinfo implementation that affects versions prior to 5.4.30 and 5.5.14. This flaw exists in the ext/standard/info.c file where the implementation fails to properly enforce string data types for several critical environment variables including PHP_AUTH_PW, PHP_AUTH_TYPE, PHP_AUTH_USER, and PHP_SELF. The root cause stems from improper type handling that allows attackers to manipulate these variables through crafted integer values, creating a scenario where the application's memory management becomes compromised. This vulnerability specifically impacts web hosting environments where PHP operates under Apache HTTP Server with mod_ssl and mod_php modules, creating a dangerous attack surface for information disclosure.
The technical exploitation of this vulnerability relies on type confusion principles that fall under CWE-128, which deals with negative array index errors, and more broadly addresses CWE-704, concerning incorrect type conversion or cast. Attackers can leverage this weakness by submitting carefully crafted integer values that cause the phpinfo function to interpret memory locations incorrectly, potentially exposing sensitive information stored in process memory. When PHP processes these variables without proper type enforcement, it can lead to memory corruption that allows attackers to read beyond intended boundaries, particularly affecting private SSL keys and other confidential data that might be stored in adjacent memory segments. The vulnerability demonstrates how improper input validation combined with type coercion can create dangerous memory access patterns that bypass normal security boundaries.
The operational impact of CVE-2014-4721 extends beyond simple information disclosure to potentially compromise entire web hosting environments, especially those utilizing mod_php with Apache HTTP Server and SSL certificates. Attackers can exploit this vulnerability to extract private SSL keys, authentication credentials, and other sensitive data that could be used for further attacks including man-in-the-middle operations, certificate impersonation, or privilege escalation within the hosting environment. The vulnerability is particularly dangerous in shared hosting environments where multiple applications run on the same server, as it could enable attackers to access data belonging to other virtual hosts or applications. Additionally, the attack vector demonstrates characteristics consistent with ATT&CK technique T1059.007, which involves the use of command and scripting interpreters, as the vulnerability allows for indirect command execution through memory manipulation. The presence of this vulnerability in PHP 5.3.x versions also indicates a broader security gap in legacy systems that may not receive timely updates, making organizations with outdated PHP installations particularly vulnerable.
Organizations should immediately implement mitigations including updating to PHP versions 5.4.30 or 5.5.14 and later, which contain the necessary patches to address the type confusion vulnerability. Security teams should also consider implementing additional monitoring for unusual phpinfo requests and memory access patterns that might indicate exploitation attempts. The patch implemented in affected versions specifically addresses the type enforcement issue by ensuring proper string conversion for the vulnerable environment variables, preventing attackers from manipulating memory through integer type coercion. System administrators should conduct comprehensive vulnerability assessments to identify any systems running affected PHP versions and ensure proper patch management procedures are in place to prevent similar vulnerabilities from being exploited in the future.