CVE-2011-1092 in PHP
Summary
by MITRE
Integer overflow in ext/shmop/shmop.c in PHP before 5.3.6 allows context-dependent attackers to cause a denial of service (crash) and possibly read sensitive memory via a large third argument to the shmop_read function.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability identified as CVE-2011-1092 represents a critical integer overflow flaw within the PHP shared memory operations extension known as shmop. This issue affects PHP versions prior to 5.3.6 and stems from improper handling of integer values during memory allocation operations. The vulnerability specifically manifests when the shmop_read function processes a large third argument that determines the number of bytes to read from shared memory segments. The integer overflow occurs during the calculation of memory boundaries, where an attacker can manipulate the input parameter to cause arithmetic overflow conditions that result in unexpected memory access patterns.
The technical implementation of this vulnerability resides in the ext/shmop/shmop.c source file where the shmop_read function performs memory operations without adequate bounds checking or integer overflow validation. When an attacker provides an excessively large value as the third parameter, the integer arithmetic used to calculate memory offsets can overflow, leading to invalid memory addresses being accessed. This overflow condition can cause the PHP process to crash due to memory access violations or potentially allow for information disclosure through reading adjacent memory locations that contain sensitive data such as stack contents, heap data, or other process memory segments.
From an operational perspective, this vulnerability creates significant risks for web applications that utilize shared memory operations for performance optimization or inter-process communication. The denial of service aspect can be exploited by malicious actors to disrupt web services, causing availability issues for legitimate users. The potential for sensitive memory reading introduces additional security concerns as attackers might extract confidential information from the process memory space, including database credentials, session tokens, or other sensitive application data. This vulnerability particularly affects systems running PHP applications that rely on shared memory for caching mechanisms, data exchange between processes, or high-performance computing scenarios where shmop functions are actively used.
The impact of this vulnerability aligns with CWE-190, which describes integer overflow conditions that can lead to memory corruption and arbitrary code execution. The ATT&CK framework categorizes this as a privilege escalation and denial of service technique, as attackers can leverage the vulnerability to disrupt services and potentially gain access to sensitive information. Organizations using affected PHP versions should prioritize immediate patching to address this vulnerability, as the integer overflow can be exploited remotely without requiring authentication. Mitigation strategies include upgrading to PHP 5.3.6 or later versions, implementing proper input validation for shmop function parameters, and monitoring system logs for unusual memory access patterns that might indicate exploitation attempts.
Security professionals should consider this vulnerability as part of broader application security assessments, particularly focusing on shared memory usage patterns in PHP applications. The vulnerability demonstrates the importance of proper integer handling in system programming and highlights the need for thorough code review processes that examine memory allocation and arithmetic operations. Organizations should also implement network segmentation and access controls to limit the potential impact of successful exploitation, while maintaining regular vulnerability scanning to identify similar issues in other system components.