CVE-2016-7414 in macOS
Summary
by MITRE
The ZIP signature-verification feature in PHP before 5.6.26 and 7.x before 7.0.11 does not ensure that the uncompressed_filesize field is large enough, which allows remote attackers to cause a denial of service (out-of-bounds memory access) or possibly have unspecified other impact via a crafted PHAR archive, related to ext/phar/util.c and ext/phar/zip.c.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-7414 represents a critical flaw in PHP's handling of PHAR archive files, specifically within the ZIP signature-verification mechanism that affects versions prior to 5.6.26 and 7.0.11. This issue stems from inadequate validation of the uncompressed_filesize field during the processing of PHAR archives, creating a potential attack vector that can be exploited by remote adversaries to manipulate memory access patterns. The vulnerability is particularly concerning because it operates at the core of PHP's archive handling functionality, which is widely used across web applications for file compression and packaging purposes.
The technical root cause of this vulnerability lies in the insufficient bounds checking within the ext/phar/util.c and ext/phar/zip.c source files where PHP processes ZIP archives. When a maliciously crafted PHAR archive is processed, the system fails to validate that the uncompressed_filesize field contains a value that is appropriate for the actual data being decompressed. This validation gap allows attackers to craft archives with malformed size parameters that can cause the application to attempt memory access operations beyond the allocated buffer boundaries. The flaw manifests as out-of-bounds memory access conditions that can lead to application crashes or potentially more severe consequences depending on how the memory corruption is exploited.
From an operational perspective, this vulnerability creates significant risks for PHP-based web applications that process user-uploaded files or handle external archive data. The remote exploitation capability means that attackers can potentially cause denial of service conditions by crashing web server processes, leading to service disruption for legitimate users. Additionally, the unspecified other impacts mentioned in the vulnerability description suggest that under certain conditions, this memory corruption could potentially be leveraged for more advanced exploitation techniques. The vulnerability affects the fundamental PHAR extension which is used extensively across PHP applications for handling compressed data, making it a widespread concern for system administrators and security teams.
The impact of this vulnerability aligns with CWE-129, which describes improper validation of array indices, and can be categorized under ATT&CK technique T1059.007 for script-based attacks. Organizations using affected PHP versions face potential compromise of their web applications and servers, particularly those that accept file uploads or process external data sources. The vulnerability's classification as a denial of service vector means that even without direct code execution capabilities, attackers can cause significant operational disruption through server crashes and resource exhaustion. System administrators should prioritize patching affected installations and implementing additional security controls such as file type validation and upload restrictions to mitigate potential exploitation attempts.
The recommended mitigation strategy involves upgrading to PHP versions 5.6.26 or 7.0.11 and later, which contain the necessary fixes for the ZIP signature-verification mechanism. Additionally, organizations should implement defensive measures including input validation for archive files, monitoring for unusual memory access patterns, and regular security assessments of PHP applications that handle external data. The vulnerability demonstrates the importance of proper bounds checking in memory management operations and highlights the critical need for comprehensive testing of archive processing functionality in web applications.