CVE-2014-3670 in PHP
Summary
by MITRE
The exif_ifd_make_value function in exif.c in the EXIF extension in PHP before 5.4.34, 5.5.x before 5.5.18, and 5.6.x before 5.6.2 operates on floating-point arrays incorrectly, which allows remote attackers to cause a denial of service (heap memory corruption and application crash) or possibly execute arbitrary code via a crafted JPEG image with TIFF thumbnail data that is improperly handled by the exif_thumbnail function.
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Analysis
by VulDB Data Team • 02/23/2022
The vulnerability described in CVE-2014-3670 represents a critical heap memory corruption flaw within PHP's EXIF extension that affects multiple version ranges including PHP 5.4.34, 5.5.18, and 5.6.2 and earlier releases. This issue stems from improper handling of floating-point arrays within the exif_ifd_make_value function located in the exif.c source file, creating a scenario where maliciously crafted JPEG images can trigger unpredictable behavior in affected PHP applications. The vulnerability specifically targets the processing of TIFF thumbnail data embedded within JPEG files, which occurs when the exif_thumbnail function attempts to parse and handle such metadata. The improper handling of floating-point values in this context creates opportunities for heap-based buffer overflows that can lead to memory corruption and system instability.
The technical exploitation of this vulnerability involves crafting a malicious JPEG image containing specially formatted TIFF thumbnail data that triggers the flawed exif_ifd_make_value function. When PHP processes such an image through its EXIF extension, the floating-point array operations become corrupted due to incorrect memory management and boundary checking. This flaw falls under the CWE-121 heap-based buffer overflow category, where the improper handling of array bounds allows attackers to write beyond allocated memory regions. The vulnerability demonstrates characteristics of both denial of service and potential code execution scenarios, making it particularly dangerous in web server environments where PHP processes user-uploaded content. The attack surface is expanded when PHP applications use the exif_thumbnail function to process images, creating a pathway for remote code execution through carefully constructed memory corruption.
The operational impact of CVE-2014-3670 extends beyond simple application crashes to potentially enable remote code execution on vulnerable systems. When exploited, the heap corruption can cause unpredictable behavior including application crashes, memory corruption that may be leveraged for privilege escalation, or in some cases direct code execution. This vulnerability is particularly concerning in web applications that accept user-uploaded images without proper validation, as attackers can upload malicious JPEG files that trigger the flaw during image processing. The vulnerability operates at the application level within the PHP runtime environment and can affect any system running vulnerable PHP versions, including web servers, content management systems, and any application that relies on PHP's EXIF processing capabilities. The ATT&CK framework categorizes this as a code injection technique when exploitation leads to remote code execution, while the memory corruption aspect aligns with privilege escalation and denial of service tactics.
Mitigation strategies for CVE-2014-3670 primarily focus on immediate version upgrades to patched PHP releases including PHP 5.4.34, 5.5.18, and 5.6.2 or later versions. Organizations should implement comprehensive patch management procedures to ensure all vulnerable PHP installations are updated promptly. Additionally, input validation and sanitization should be strengthened at application level by implementing strict file type checking, image validation routines, and content security policies that prevent processing of untrusted image files. Security measures should include monitoring for unusual application behavior, implementing proper error handling to prevent crash exploitation, and deploying web application firewalls that can detect and block suspicious image processing requests. The vulnerability highlights the importance of proper memory management in interpreted languages and underscores the need for regular security audits of PHP extensions and libraries that handle binary data processing. Organizations should also consider implementing sandboxing techniques for image processing operations and establishing robust incident response procedures to address potential exploitation attempts.