CVE-2014-3479 in Mac OS X
Summary
by MITRE
The cdf_check_stream_offset function in cdf.c in file before 5.19, as used in the Fileinfo component in PHP before 5.4.30 and 5.5.x before 5.5.14, relies on incorrect sector-size data, which allows remote attackers to cause a denial of service (application crash) via a crafted stream offset in a CDF file.
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Analysis
by VulDB Data Team • 02/20/2022
The vulnerability identified as CVE-2014-3479 represents a critical denial of service flaw affecting PHP applications that process Compound Document File (CDF) format files through the Fileinfo component. This vulnerability specifically targets the cdf_check_stream_offset function within the cdf.c file, which serves as a core component in PHP's file type detection system. The issue manifests when PHP processes CDF files that contain malformed or crafted stream offset data, leading to application instability and potential system crashes. The vulnerability affects PHP versions prior to 5.4.30 and 5.5.14, making it particularly concerning given the widespread adoption of these PHP versions in web applications and content management systems.
The technical root cause of this vulnerability stems from improper validation of sector-size data within CDF file structures. When the cdf_check_stream_offset function processes a CDF file, it relies on incorrect or manipulated sector-size information to determine stream offsets. This flawed approach creates a condition where an attacker can craft a CDF file with maliciously constructed stream offset values that cause the application to attempt memory access operations beyond valid boundaries. The vulnerability operates at the level of file parsing and memory management, where the application's handling of CDF structures fails to properly validate input data before proceeding with calculations. This type of flaw falls under the CWE-129 weakness category, which encompasses issues related to insufficient validation of the boundaries of a resource, specifically affecting memory access operations during file processing.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a potential vector for more sophisticated attacks within the broader context of application security. Remote attackers can exploit this weakness by uploading or otherwise presenting a specially crafted CDF file to a vulnerable PHP application, resulting in application crashes that can disrupt service availability. The vulnerability's characteristics align with ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion or application instability. When exploited at scale, these vulnerabilities can lead to cascading failures in web applications that rely on PHP for file type detection, potentially affecting multiple users and systems within a network infrastructure.
Mitigation strategies for CVE-2014-3479 primarily focus on immediate version upgrades to patched PHP releases that address the sector-size validation issues in CDF file processing. System administrators should prioritize updating their PHP installations to versions 5.4.30 or 5.5.14 and later, which contain the necessary code modifications to properly validate sector-size data and prevent the exploitation of stream offset calculations. Additionally, implementing proper input validation and sanitization measures for file uploads can provide defense-in-depth protection against similar vulnerabilities. Organizations should also consider restricting file type detection capabilities for untrusted file inputs, particularly when dealing with binary formats like CDF that are prone to complex parsing vulnerabilities. Network-level protections such as intrusion detection systems can help identify exploitation attempts, while monitoring for unusual application crash patterns can aid in early detection of potential attacks targeting this vulnerability. The remediation approach should also include comprehensive testing of updated PHP installations to ensure that the patched functionality correctly handles various CDF file structures without introducing regressions in file processing capabilities.