CVE-2015-9339 in wp-file-upload Plugin
Summary
by MITRE
The wp-file-upload plugin before 2.7.1 for WordPress has insufficient restrictions on upload of .js files.
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Analysis
by VulDB Data Team • 11/28/2023
The wp-file-upload plugin vulnerability CVE-2015-9339 represents a critical security flaw in WordPress plugin ecosystems that allowed unauthorized execution of malicious javascript code. This vulnerability specifically affected versions prior to 2.7.1 of the wp-file-upload plugin, which is widely used for file management capabilities within wordpress environments. The issue stems from inadequate input validation and file type restriction mechanisms that failed to properly sanitize or block javascript files from being uploaded to the web server. The vulnerability falls under the category of insecure file upload practices that are commonly exploited in web application attacks.
The technical flaw manifests in the plugin's failure to implement proper file extension validation and content inspection for javascript files. When users attempted to upload .js files through the plugin interface, the system did not adequately verify whether the uploaded file contained malicious code or simply matched the expected file extension. This weakness creates a path for attackers to bypass security controls and upload potentially harmful javascript payloads that could execute within the context of the victim's browser. The vulnerability is particularly dangerous because javascript files can contain malicious code that performs actions such as credential theft, session hijacking, or redirection to malicious sites. This flaw aligns with CWE-434 which describes insecure file upload vulnerabilities where applications fail to restrict or validate file uploads.
The operational impact of this vulnerability extends beyond simple privilege escalation as it creates persistent attack vectors within wordpress installations. Attackers could leverage this vulnerability to upload malicious javascript files that would remain undetected on the server, potentially compromising all users who accessed those files. The threat is exacerbated by the fact that wordpress plugins often have elevated privileges and can interact with database systems, making the attack surface significantly larger than typical web application vulnerabilities. This vulnerability could enable attackers to establish persistent backdoors, steal user credentials, or manipulate content management systems through the compromised plugin. The risk is further amplified when considering that many wordpress installations lack proper monitoring and file integrity checks that might detect unauthorized file modifications.
Security mitigations for this vulnerability require immediate plugin updates to version 2.7.1 or later where proper file validation has been implemented. Organizations should also implement comprehensive file upload restrictions that go beyond simple extension checking to include content inspection and proper file type validation. Network security controls such as web application firewalls should be configured to monitor and block suspicious file upload activities. The remediation process must include thorough security auditing of all installed plugins to identify similar vulnerabilities in the wordpress ecosystem. Additionally, implementing proper access controls and regular security assessments can help prevent exploitation of such vulnerabilities. This case demonstrates the importance of maintaining up-to-date software components and implementing defense-in-depth strategies that protect against multiple attack vectors. The vulnerability also highlights the need for proper input validation and the principle of least privilege in plugin development and deployment practices.