Frontend File Manager Plugin WordPress Stored XSS

Executive Summary

The Frontend File Manager Plugin for WordPress, up to version 23.6, contains a Stored Cross-Site Scripting (XSS) vulnerability. This happens because the plugin does not properly sanitize or escape filenames submitted through its frontend file-rename feature. Malicious scripts can be embedded in these filenames and stored as post meta data. When an administrator views the file management interface, these scripts are rendered, potentially executing harmful actions.

This vulnerability can be exploited by users with Subscriber-level access or higher, making it a significant security risk.

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Impact Analysis

This vulnerability allows attackers with low-level access (Subscriber or above) to inject malicious scripts that execute when an administrator views the file manager. This can lead to unauthorized actions such as stealing administrator session cookies, defacing the admin interface, or performing other malicious activities within the admin context.

Because the attack is stored and triggered in the admin interface, it can compromise the security and integrity of the WordPress site, potentially leading to further exploitation or data breaches.

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Detection Guidance

This vulnerability can be detected by checking if the Frontend File Manager Plugin version is 23.6 or below, as these versions do not sanitize or escape filenames submitted to the frontend file-rename endpoint.

Since the vulnerability involves stored malicious scripts in filenames, one detection method is to inspect the post meta data related to file renames for suspicious or script-like content.

There are no specific commands provided in the resources, but general approaches include:

• Query the WordPress database for post meta entries related to file renames and look for suspicious script tags or JavaScript code.
• Review the admin File Manager listing for any unusual or unexpected content in filenames.
• Check the plugin version installed on your WordPress site using WP-CLI: `wp plugin list` and verify if the version is 23.6 or lower.

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Mitigation Strategies

Immediate mitigation steps include:

• Restrict Subscriber-level users from accessing the frontend file-rename functionality if possible.
• Manually sanitize or validate filenames submitted through the frontend file-rename endpoint to prevent script injection.
• Monitor and remove any suspicious or malicious filenames stored as post meta.
• Limit administrative users' exposure to the File Manager listing until a patch or update is available.

Note that no known fix is currently available for this vulnerability, so these steps are temporary mitigations.

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Compliance Impact

The vulnerability allows Stored Cross-Site Scripting (XSS) attacks via the file rename functionality, which can lead to unauthorized script execution in the admin interface. This type of vulnerability can compromise the confidentiality and integrity of administrative operations and potentially expose sensitive data.

Such security weaknesses may impact compliance with common standards and regulations like GDPR and HIPAA, which require organizations to protect personal data and maintain secure systems to prevent unauthorized access or data breaches.

Since the vulnerability can be exploited by users with Subscriber-level access to execute scripts in an administrator's context, it increases the risk of privilege escalation and data exposure, which are critical concerns under these regulations.

However, no specific compliance impact or mitigation guidance is provided in the available resources.

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