CVE-2014-0236 in File
Summary
by MITRE
file before 5.18, as used in the Fileinfo component in PHP before 5.6.0, allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a zero root_storage value in a CDF file, related to cdf.c and readcdf.c.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2014-0236 represents a critical denial of service flaw affecting PHP's Fileinfo component prior to version 5.6.0. This issue stems from improper handling of Compound Document File (CDF) structures, specifically when processing files with a zero root_storage value. The vulnerability manifests through the cdf.c and readcdf.c source files that form part of PHP's file type detection mechanism, which is commonly utilized for content sniffing and file validation purposes.
The technical exploitation of this vulnerability occurs when PHP's Fileinfo extension attempts to process a malformed CDF file containing a zero root_storage field. This condition triggers a NULL pointer dereference within the file parsing routines, causing the PHP application to crash abruptly. The flaw exists at the core parsing logic where the application fails to validate the integrity of CDF structure elements before attempting to access memory locations. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions, making it particularly dangerous in web applications where file uploads or content analysis are common operations.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by remote attackers to systematically crash PHP applications running vulnerable versions. Attackers can craft malicious CDF files with the specific zero root_storage value and submit them through file upload mechanisms or content analysis functions, leading to application crashes that can be exploited for denial of service attacks. This vulnerability particularly affects web servers that utilize PHP's Fileinfo extension for automatic file type detection, which is commonly implemented in content management systems, file sharing platforms, and any application that performs file validation or content analysis.
Mitigation strategies for CVE-2014-0236 primarily involve upgrading to PHP version 5.6.0 or later where the vulnerability has been resolved through proper input validation and memory handling. System administrators should also implement additional defensive measures such as restricting file upload capabilities, implementing strict file type validation, and monitoring for suspicious file patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for "Network Denial of Service" as it enables attackers to disrupt services through application-level crashes. Organizations should also consider implementing web application firewalls and content filtering mechanisms to detect and block malicious CDF files before they can be processed by vulnerable PHP installations.