CVE-2019-11050 in PHP
Summary
by MITRE
When PHP EXIF extension is parsing EXIF information from an image, e.g. via exif_read_data() function, in PHP versions 7.2.x below 7.2.26, 7.3.x below 7.3.13 and 7.4.0 it is possible to supply it with data what will cause it to read past the allocated buffer. This may lead to information disclosure or crash.
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Analysis
by VulDB Data Team • 03/16/2024
The vulnerability identified as CVE-2019-11050 represents a critical buffer over-read condition within the PHP EXIF extension that affects multiple PHP version streams including 7.2.x below 7.2.26, 7.3.x below 7.3.13, and PHP 7.4.0. This flaw occurs during the processing of EXIF metadata from image files through the exif_read_data() function, which is commonly used to extract technical information embedded within digital photographs and other image formats. The vulnerability stems from inadequate bounds checking within the EXIF parsing logic, specifically when handling malformed or crafted EXIF data structures that exceed the allocated memory boundaries.
The technical implementation of this vulnerability involves the EXIF extension's failure to properly validate the length and structure of EXIF data segments before attempting to read them into memory buffers. When a maliciously crafted image file is processed, the parser continues reading beyond the allocated buffer space, potentially accessing adjacent memory regions that may contain sensitive data such as stack contents, heap data, or other process memory. This behavior aligns with CWE-125, which describes out-of-bounds read vulnerabilities that can lead to information disclosure and system instability. The vulnerability can be exploited through various attack vectors including web applications that process user-uploaded images, content management systems, and any PHP application that utilizes the exif_read_data() function without proper input sanitization.
The operational impact of CVE-2019-11050 extends beyond simple crash conditions to include potential information disclosure that could expose sensitive system data or application secrets. Attackers can leverage this vulnerability to construct malicious image files that, when processed by vulnerable PHP applications, cause the system to read and potentially leak memory contents that may include authentication tokens, database connection details, or other confidential information. This makes the vulnerability particularly dangerous in web environments where user-uploaded content is common, as it can be exploited through server-side request forgery attacks or by targeting applications that automatically process and display image metadata. The vulnerability's classification under ATT&CK technique T1059.007 for script-based attacks and T1566 for spearphishing attachments demonstrates its potential for exploitation in various attack scenarios involving image processing applications.
Mitigation strategies for CVE-2019-11050 primarily focus on immediate version upgrades to patched PHP releases, specifically PHP 7.2.26, 7.3.13, or 7.4.0 and later versions. Organizations should implement comprehensive input validation measures that sanitize all image uploads before processing, including implementing strict file format validation and size limitations. Security measures should also include monitoring for unusual memory access patterns and implementing proper error handling that prevents the exposure of raw memory contents. Additional protective measures include deploying web application firewalls that can detect and block suspicious image file patterns, implementing strict file upload policies that restrict image types to known safe formats, and ensuring that PHP applications running on vulnerable versions have proper access controls and least privilege principles applied to minimize potential damage from successful exploitation attempts.