CVE-2015-3307 in PHP
Summary
by MITRE
The phar_parse_metadata function in ext/phar/phar.c in PHP before 5.4.40, 5.5.x before 5.5.24, and 5.6.x before 5.6.8 allows remote attackers to cause a denial of service (heap metadata corruption) or possibly have unspecified other impact via a crafted tar archive.
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Analysis
by VulDB Data Team • 05/20/2022
The vulnerability identified as CVE-2015-3307 represents a critical heap metadata corruption issue within PHP's phar extension that affects multiple version ranges including PHP 5.4.x before 5.4.40, 5.5.x before 5.5.24, and 5.6.x before 5.6.8. This flaw resides in the phar_parse_metadata function located in ext/phar/phar.c, which is responsible for parsing and processing phar archives. The vulnerability stems from insufficient input validation and memory management when handling specially crafted tar archives, creating a potential vector for both denial of service attacks and arbitrary code execution. The issue manifests when PHP processes maliciously constructed archive files that exploit memory corruption patterns in the heap allocation mechanisms, potentially leading to unpredictable system behavior.
The technical implementation of this vulnerability involves the manipulation of tar archive metadata during the parsing process, where the phar_parse_metadata function fails to properly validate the structure and content of archive headers. Attackers can craft specific tar archives containing malformed metadata entries that trigger buffer overflows or memory corruption when PHP attempts to parse these structures. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, which is classified as a memory safety issue that can lead to arbitrary code execution. The vulnerability is particularly dangerous because it can be exploited through web applications that process user-uploaded files or when PHP applications attempt to parse external archive data, making it a significant concern for web server environments.
From an operational perspective, this vulnerability creates substantial risk for PHP-based web applications and servers that handle file uploads or archive processing. The potential impact includes complete system compromise when attackers successfully exploit the heap corruption to execute arbitrary code, as well as denial of service conditions that can render web applications unavailable to legitimate users. The attack surface is broad since many PHP applications process user-provided files, and the vulnerability can be triggered through various vectors including file upload handlers, archive extraction functions, and content delivery mechanisms. According to ATT&CK framework, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1499.004 (Network Denial of Service: Application Exhaustion) techniques, as it can be used to cause service disruption or gain unauthorized access to systems.
The mitigation strategy for CVE-2015-3307 requires immediate patching of affected PHP installations to versions that contain the necessary security fixes. Organizations should implement comprehensive patch management procedures to ensure all PHP instances are updated promptly, particularly those running in production environments. Additionally, administrators should implement strict file validation and sanitization measures for any file upload functionality, including MIME type checking, file extension validation, and content scanning to prevent malicious archives from being processed. Network-level protections such as web application firewalls and intrusion detection systems can provide additional defense-in-depth layers, while monitoring systems should be configured to detect unusual file processing patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date software versions and implementing proper input validation controls to prevent memory corruption exploits that can lead to complete system compromise.