CVE-2019-11035 in PHP
Summary
by MITRE
When processing certain files, PHP EXIF extension in versions 7.1.x below 7.2.8, 7.2.x below 7.2.17 and 7.3.x below 7.3.4 can be caused to read past allocated buffer in exif_iif_add_value function. This may lead to information disclosure or crash.
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Analysis
by VulDB Data Team • 09/04/2023
The vulnerability identified as CVE-2019-11035 resides within the PHP EXIF extension, a component responsible for processing exchangeable image file format data commonly found in digital photographs. This flaw manifests in specific versions of PHP including 7.1.x prior to 7.2.8, 7.2.x prior to 7.2.17, and 7.3.x prior to 7.3.4, representing a critical buffer overflow condition that can be exploited through maliciously crafted image files. The vulnerability is classified under CWE-125 as an out-of-bounds read, where the exif_iif_add_value function fails to properly validate buffer boundaries during file processing operations.
The technical exploitation of this vulnerability occurs when the PHP EXIF extension attempts to parse image metadata, specifically within the exif_iif_add_value function which handles the addition of values to the image information structure. When processing certain malformed or specially crafted EXIF data, the function reads beyond the allocated memory buffer, potentially accessing adjacent memory locations that contain sensitive data or system information. This behavior can result in information disclosure where confidential data from memory is inadvertently exposed to attackers, or cause application crashes that lead to denial of service conditions. The vulnerability represents a classic buffer overflow scenario where insufficient bounds checking allows arbitrary memory access patterns.
The operational impact of CVE-2019-11035 extends beyond simple application instability, as it can be leveraged for information disclosure attacks that may reveal sensitive system information, user data, or application internals. Attackers can craft malicious image files that, when processed by vulnerable PHP applications, trigger the buffer overflow condition and potentially extract memory contents that could aid in further exploitation attempts. This vulnerability is particularly concerning in web applications that accept user-uploaded images or process EXIF data from external sources, as it provides a direct pathway for remote code execution or information leakage through carefully constructed input data. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter usage, as exploitation may involve manipulating image processing routines to achieve unauthorized access.
Mitigation strategies for this vulnerability require immediate patching of affected PHP versions to the recommended secure releases, specifically upgrading to PHP 7.2.8, 7.2.17, or 7.3.4 respectively. Organizations should implement input validation measures that restrict or sanitize EXIF data processing, particularly when handling user-uploaded content, and consider disabling EXIF processing entirely if not required for application functionality. Additionally, deploying web application firewalls and implementing proper access controls can help reduce the attack surface and prevent exploitation attempts. Security monitoring should focus on detecting unusual image processing patterns or memory access behaviors that might indicate exploitation attempts, while regular security assessments should verify that all PHP installations are updated to patched versions. The vulnerability demonstrates the importance of proper memory management and input validation in preventing buffer overflow conditions that can lead to serious security implications across web applications.