CVE-2015-0232 in PHP
Summary
by MITRE
The exif_process_unicode function in ext/exif/exif.c in PHP before 5.4.37, 5.5.x before 5.5.21, and 5.6.x before 5.6.5 allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized pointer free and application crash) via crafted EXIF data in a JPEG image.
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Analysis
by VulDB Data Team • 03/08/2022
The vulnerability identified as CVE-2015-0232 represents a critical memory corruption flaw within the PHP exif extension that affects multiple PHP versions including 5.4.36 and earlier, 5.5.20 and earlier, and 5.6.4 and earlier. This vulnerability resides in the exif_process_unicode function located in ext/exif/exif.c, which processes EXIF metadata embedded within JPEG images. The flaw manifests when PHP encounters malformed or specially crafted EXIF data during image processing operations, creating a dangerous condition that can be exploited by remote attackers to execute arbitrary code or induce denial of service conditions.
The technical nature of this vulnerability stems from improper memory management within the exif extension's Unicode processing routine. Specifically, the exif_process_unicode function fails to properly initialize memory pointers before attempting to free them, leading to a use-after-free condition that can be exploited through carefully constructed EXIF metadata. This uninitialized pointer free vulnerability creates a scenario where an attacker can manipulate the memory layout of the PHP process, potentially allowing for code execution or application crashes. The vulnerability operates at the application level within the PHP interpreter, making it particularly dangerous in web environments where PHP processes user-uploaded images containing malicious EXIF data.
The operational impact of CVE-2015-0232 extends beyond simple denial of service to encompass potential remote code execution capabilities that can compromise entire web applications. When a vulnerable PHP application processes JPEG images containing crafted EXIF data, the application may crash or, in more severe cases, allow attackers to inject and execute arbitrary code on the server. This vulnerability directly affects web applications that utilize PHP's image processing capabilities, particularly those accepting user uploads, image galleries, or any functionality that processes EXIF metadata from JPEG files. The exploitability of this vulnerability is heightened in environments where PHP applications handle untrusted image data without proper validation or sanitization.
Organizations affected by this vulnerability should prioritize immediate patching of all PHP installations running versions prior to the fixed releases. The recommended mitigation strategy involves upgrading to PHP 5.4.37, 5.5.21, or 5.6.5 respectively, depending on the specific PHP version in use. Additional defensive measures should include implementing strict input validation for image uploads, sanitizing EXIF metadata before processing, and employing web application firewalls to detect and block suspicious image file content. From a cybersecurity perspective, this vulnerability aligns with CWE-416, which addresses use after free conditions, and represents a common vector for privilege escalation attacks in web application environments. The ATT&CK framework categorizes this as a code injection technique under the application layer, specifically targeting memory corruption vulnerabilities in interpreted languages.
The vulnerability demonstrates the critical importance of proper memory management in interpreted languages and highlights the risks associated with third-party extension libraries within web application frameworks. PHP's exif extension, while commonly used for image metadata processing, became a vector for exploitation due to inadequate error handling and memory safety checks. This incident underscores the necessity for comprehensive security testing of all application components, particularly those handling external data inputs, and reinforces the importance of maintaining up-to-date software versions to protect against known vulnerabilities. Organizations should implement regular security assessments and vulnerability scanning procedures to identify and remediate similar memory corruption issues across their PHP-based applications and infrastructure components.