CVE-2014-9427 in PHP
Summary
by MITRE
sapi/cgi/cgi_main.c in the CGI component in PHP through 5.4.36, 5.5.x through 5.5.20, and 5.6.x through 5.6.4, when mmap is used to read a .php file, does not properly consider the mapping's length during processing of an invalid file that begins with a # character and lacks a newline character, which causes an out-of-bounds read and might (1) allow remote attackers to obtain sensitive information from php-cgi process memory by leveraging the ability to upload a .php file or (2) trigger unexpected code execution if a valid PHP script is present in memory locations adjacent to the mapping.
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Analysis
by VulDB Data Team • 03/01/2022
The vulnerability identified as CVE-2014-9427 represents a critical out-of-bounds memory read flaw within PHP's CGI component that affects multiple versions including 5.4.36 and earlier, 5.5.20 and earlier, and 5.6.4 and earlier. This issue specifically manifests when the PHP CGI interface utilizes memory mapping to process php files, creating a dangerous condition that can be exploited remotely. The flaw occurs in the sapi/cgi/cgi_main.c file where the system fails to properly account for the mapping length when handling malformed php files that begin with a hash character followed by content without a trailing newline. This particular combination creates a scenario where the memory mapping process reads beyond the intended boundaries of the file data.
The technical implementation of this vulnerability stems from improper boundary checking during file processing within the PHP CGI environment. When a malicious user uploads a specially crafted .php file that starts with a # character and lacks a newline, the memory mapping routine incorrectly calculates the effective length of the mapped region. This miscalculation results in the system reading memory locations that extend beyond the actual file boundaries, potentially exposing sensitive information stored in adjacent memory regions. The vulnerability is particularly dangerous because it leverages the legitimate file upload functionality that many web applications utilize, making it difficult to distinguish between normal and malicious file processing.
The operational impact of this vulnerability spans multiple attack vectors that can compromise system security and data integrity. Remote attackers can exploit this flaw to extract sensitive information from the php-cgi process memory, potentially accessing database credentials, session tokens, or other confidential data stored in memory. Additionally, the vulnerability creates conditions where adjacent memory locations containing valid PHP code could be inadvertently executed, leading to unexpected code execution. This dual nature makes the vulnerability particularly dangerous as it can be used for both information disclosure and arbitrary code execution attacks. The attack surface is broad since many web applications rely on PHP CGI for processing dynamic content, and the exploit can be triggered through simple file upload mechanisms.
Security professionals should consider this vulnerability in the context of the CWE-125 Out-of-Bounds Read weakness which is categorized under the Common Weakness Enumeration framework. The ATT&CK framework would classify this as a privilege escalation technique through memory corruption, potentially enabling an attacker to move laterally within a system. Organizations should immediately update their PHP installations to versions beyond the affected releases, as the vulnerability exists in multiple version streams and can be exploited remotely. System administrators should also implement network-level protections such as web application firewalls to monitor and block suspicious file upload patterns, and conduct thorough code reviews to identify potential memory handling issues in custom PHP applications. The vulnerability demonstrates the importance of proper boundary checking in memory management operations and highlights the need for comprehensive security testing of file processing components in web applications.