CVE-2003-0166 in PHP
Summary
by MITRE
Integer signedness error in emalloc() function for PHP before 4.3.2 allow remote attackers to cause a denial of service (memory consumption) and possibly execute arbitrary code via negative arguments to functions such as (1) socket_recv, (2) socket_recvfrom, and possibly other functions.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability identified as CVE-2003-0166 represents a critical integer signedness error within the emalloc() function of PHP versions prior to 4.3.2. This flaw resides in the memory allocation mechanism that governs how PHP handles dynamic memory requests during program execution. The vulnerability specifically manifests when negative arguments are passed to socket-related functions, particularly socket_recv and socket_recvfrom, which are fundamental components of PHP's socket programming capabilities. The underlying issue stems from improper handling of signed integer values during memory allocation calculations, creating a condition where negative values can be interpreted as extremely large positive numbers.
The technical exploitation of this vulnerability occurs through the manipulation of socket function parameters that accept length or size arguments. When these functions receive negative values, the signedness error causes the emalloc() function to allocate an enormous amount of memory, potentially leading to system memory exhaustion and subsequent denial of service conditions. This memory consumption attack can be executed remotely without requiring authentication, making it particularly dangerous in networked environments. The vulnerability extends beyond simple denial of service to potentially allow arbitrary code execution, as the improper memory allocation can corrupt memory structures and create opportunities for code injection attacks.
From an operational perspective, this vulnerability poses significant risks to web servers running PHP applications, particularly those that handle network communications or user input through socket operations. The impact extends to any system where PHP processes receive data from external sources through socket functions, including web applications that process network requests, file transfers, or real-time communication systems. The vulnerability's remote exploitability means that attackers can target systems from outside the network perimeter without requiring local access or credentials, making it a particularly attractive target for automated attacks. The potential for arbitrary code execution adds an additional layer of risk, as successful exploitation could lead to complete system compromise.
The vulnerability aligns with CWE-190, which addresses integer overflow and signedness errors, and demonstrates characteristics consistent with ATT&CK technique T1059 for command and scripting interpreter, as the potential for arbitrary code execution enables attackers to establish persistent access. Organizations should implement immediate mitigations including upgrading to PHP version 4.3.2 or later, which contains the necessary patches to address the signedness error in emalloc(). Additional protective measures include implementing input validation for socket function parameters, monitoring for unusual memory consumption patterns, and deploying network segmentation to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of proper integer handling in memory management functions and underscores the critical need for thorough code review processes that examine signedness considerations in low-level system functions.