CVE-2019-11344 in Pluck
Summary
by MITRE
data/inc/files.php in Pluck 4.7.8 allows remote attackers to execute arbitrary code by uploading a .htaccess file that specifies SetHandler x-httpd-php for a .txt file, because only certain PHP-related filename extensions are blocked.
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Analysis
by VulDB Data Team • 09/04/2023
The vulnerability identified as CVE-2019-11344 resides within the file handling mechanisms of Pluck version 4.7.8, specifically in the data/inc/files.php component. This issue represents a critical security flaw that enables remote attackers to execute arbitrary code through strategic file upload manipulation. The vulnerability stems from insufficient input validation and restrictive file extension filtering within the application's file management system, creating an avenue for malicious exploitation that can compromise the entire web application infrastructure.
The technical implementation of this vulnerability exploits a fundamental weakness in the application's file extension filtering mechanism. Attackers can bypass the existing security controls by uploading a specially crafted .htaccess file that contains the directive SetHandler x-httpd-php for .txt files. This technique leverages the Apache web server's mod_php module configuration to reinterpret text files as executable PHP code, effectively circumventing the application's intended security boundaries. The flaw occurs because the system only blocks specific PHP-related filename extensions while failing to account for alternative methods of code execution through server configuration files, creating a significant bypass opportunity.
From an operational impact perspective, this vulnerability presents a severe threat to web application security as it allows attackers to execute arbitrary code remotely without requiring authentication or elevated privileges. The successful exploitation enables attackers to gain full control over the affected system, potentially leading to complete compromise of the web server, data exfiltration, and establishment of persistent backdoors. The vulnerability affects the confidentiality, integrity, and availability of the targeted application, with potential cascading effects on dependent systems and services within the network infrastructure.
The attack vector for this vulnerability aligns with the ATT&CK framework's technique T1190 - Exploit Public-Facing Application, specifically targeting the application's file upload functionality. This weakness can be classified under CWE-434 Unrestricted Upload of File with Dangerous Type, which emphasizes the critical importance of proper file validation and content verification in web applications. The vulnerability demonstrates the fundamental principle that security by obscurity or incomplete filtering mechanisms can be easily circumvented by attackers who understand the underlying system configurations and available attack vectors.
Effective mitigation strategies for this vulnerability require immediate implementation of comprehensive file validation controls that go beyond simple extension filtering. Organizations should implement strict content-type checking, enforce proper file format validation, and utilize whitelisting approaches for acceptable file types rather than relying on blacklisting methods. Additionally, the application should be configured to prevent execution of .htaccess files in upload directories and implement proper file permissions that restrict executable privileges. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in file handling mechanisms, ensuring that all potential attack vectors are properly addressed. The remediation process should also include updating to the latest version of Pluck where this vulnerability has been patched and implementing network-level controls to monitor and prevent suspicious file upload activities.