CVE-2014-9653 in File
Summary
by MITRE
readelf.c in file before 5.22, as used in the Fileinfo component in PHP before 5.4.37, 5.5.x before 5.5.21, and 5.6.x before 5.6.5, does not consider that pread calls sometimes read only a subset of the available data, which allows remote attackers to cause a denial of service (uninitialized memory access) or possibly have unspecified other impact via a crafted ELF file.
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Analysis
by VulDB Data Team • 03/09/2022
The vulnerability identified as CVE-2014-9653 represents a critical flaw in the fileinfo component of PHP applications, specifically within the readelf.c implementation that processes ELF (Executable and Linkable Format) files. This issue affects multiple PHP versions including 5.4.x through 5.4.36, 5.5.x through 5.5.20, and 5.6.x through 5.6.4, making it a widespread concern across the PHP ecosystem. The vulnerability stems from improper handling of pread system calls during ELF file parsing operations, where the application fails to account for partial data reads that can occur during file I/O operations.
The technical root cause of this vulnerability lies in the improper implementation of data reading mechanisms within the fileinfo extension. When processing ELF files, the readelf.c module employs pread calls to read specific portions of executable files, but it does not adequately handle cases where these system calls return fewer bytes than requested. This behavior can occur due to various factors including file system limitations, concurrent access issues, or hardware-level constraints. The flaw creates a scenario where the application continues processing with incomplete data, leading to uninitialized memory access patterns that can result in unpredictable behavior.
From an operational perspective, this vulnerability presents significant risks to PHP-based web applications that utilize the fileinfo extension for file type detection or content analysis. Remote attackers can craft specially designed ELF files that exploit this weakness to trigger denial of service conditions, causing application crashes or system instability. The potential for unspecified other impacts suggests that attackers might be able to leverage this vulnerability for more sophisticated attacks, potentially including information disclosure or privilege escalation depending on the execution environment. The vulnerability is particularly concerning in web server contexts where PHP applications process user-uploaded files or access external resources.
The impact of CVE-2014-9653 aligns with CWE-129, which addresses improper validation of array indices, and demonstrates characteristics consistent with ATT&CK technique T1203, involving the exploitation of input validation weaknesses to achieve system compromise. Organizations running affected PHP versions face substantial risk of service disruption and potential security breaches, particularly in environments where PHP applications process untrusted file inputs. The vulnerability's classification as a denial of service issue indicates that even without direct exploitation for privilege escalation, the impact on system availability and service integrity remains severe.
Mitigation strategies for this vulnerability include immediate patching of affected PHP installations to versions that contain the necessary fixes for proper pread handling. System administrators should also implement input validation measures to restrict file type processing and consider implementing additional monitoring for unusual file access patterns. Organizations should conduct comprehensive vulnerability assessments to identify all PHP installations that might be exposed to this risk, particularly those handling user uploads or external file processing. The fix typically involves ensuring that all pread calls properly verify the number of bytes actually read and handle partial reads gracefully, preventing uninitialized memory access conditions that could lead to system instability or potential exploitation.