CVE-2017-14719 in WordPress
Summary
by MITRE
Before version 4.8.2, WordPress was vulnerable to a directory traversal attack during unzip operations in the ZipArchive and PclZip components.
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Analysis
by VulDB Data Team • 01/14/2021
WordPress versions prior to 4.8.2 contained a critical directory traversal vulnerability within their zip file handling components, specifically affecting both ZipArchive and PclZip libraries. This vulnerability allowed attackers to exploit the decompression process by manipulating file paths in zip archives, potentially enabling them to write files to arbitrary locations on the server filesystem. The flaw occurred during the extraction phase when the application failed to properly validate or sanitize file paths contained within zip archives, creating a pathway for malicious actors to bypass normal file access controls and execute unauthorized operations.
The technical exploitation of this vulnerability leveraged the inherent behavior of zip file decompression where archive entries could contain relative path references such as ../ or ..\ that would traverse directories when extracted. Attackers could craft malicious zip files containing specially formatted paths that would cause the unzip process to write files outside of the intended extraction directory, potentially overwriting critical system files or creating backdoor access points. This weakness directly corresponds to CWE-22, known as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')", which is a fundamental security flaw in file system access controls. The vulnerability was particularly dangerous because it could be exploited through legitimate WordPress update mechanisms or plugin installation processes, making it difficult to detect and prevent without proper input validation.
The operational impact of this vulnerability was severe for WordPress installations, as it could enable attackers to gain unauthorized access to server resources and potentially achieve remote code execution. Successful exploitation allowed attackers to overwrite configuration files, inject malicious code into web applications, or create persistent backdoors that could maintain access even after system restarts. This vulnerability was particularly concerning because it affected the core WordPress update and plugin installation mechanisms, meaning that any user with privileges to upload or install plugins could potentially exploit this flaw. The attack surface extended beyond simple file overwrite operations, as it could be combined with other vulnerabilities to create more sophisticated attack chains that could lead to complete system compromise. Organizations running vulnerable WordPress installations faced significant risk of data breaches, service disruption, and potential regulatory compliance violations.
The mitigation strategy for this vulnerability required immediate patching of WordPress installations to version 4.8.2 or later, which included enhanced input validation and path sanitization in the zip handling components. Additionally, administrators should implement strict file upload restrictions, validate all zip file contents before extraction, and monitor system logs for suspicious file operations. Network-level controls such as firewall rules to restrict access to WordPress administrative interfaces and regular security audits of installed plugins and themes became essential defensive measures. This vulnerability highlighted the importance of secure coding practices in third-party libraries and the critical need for regular security updates, aligning with ATT&CK technique T1059.007 for execution through archive extraction. Organizations should also consider implementing application whitelisting policies and regular vulnerability scanning to identify similar weaknesses in other components of their web applications, as this type of vulnerability demonstrates how seemingly benign file operations can create significant security risks when proper input validation is not implemented.