Authenticated Stored XSS in LiquidFiles Upload File Shares API

Executive Summary

This vulnerability is an authenticated stored cross-site scripting (XSS) issue in the Upload File Shares API of LiquidFiles version 4.2.7. It allows attackers who have authentication to inject malicious JavaScript or HTML code by crafting a payload in the Name parameter.

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Impact Analysis

Exploitation of this vulnerability can lead to execution of arbitrary JavaScript or HTML in the context of users interacting with the affected API. This can result in unauthorized actions, data theft, session hijacking, or other malicious activities performed by the attacker.

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Compliance Impact

The vulnerability allows attackers to execute arbitrary JavaScript in a victim's browser by injecting malicious payloads into the file upload system, potentially leading to unauthorized access or manipulation of sensitive data.

Such unauthorized access or data manipulation could impact compliance with data protection regulations like GDPR and HIPAA, which require safeguarding personal and sensitive information against unauthorized access and ensuring data integrity.

The vulnerability bypasses Content Security Policy protections and can lead to full instance compromise if administrative users are targeted, increasing the risk of data breaches and non-compliance with security standards.

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Detection Guidance

Detection of this vulnerability involves identifying if the LiquidFiles instance is running version 4.2.7, which is known to be vulnerable.

Since the vulnerability exploits the Upload File Shares API by injecting malicious payloads into the Name parameter, monitoring HTTP requests to this API endpoint for suspicious or crafted payloads can help detect exploitation attempts.

Additionally, reviewing activity logs for filenames containing unexpected HTML or JavaScript code may indicate exploitation.

Specific commands are not provided in the resources, but general approaches include:

• Using network monitoring tools (e.g., tcpdump, Wireshark) to capture and analyze HTTP POST requests to the file upload API for suspicious payloads.
• Querying the LiquidFiles database or logs for entries in the Name parameter containing HTML or JavaScript tags.
• Checking the installed LiquidFiles version via its interface or command line to confirm if it is version 4.2.7.

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Mitigation Strategies

The primary immediate mitigation step is to upgrade LiquidFiles from version 4.2.7 to the patched version 4.2.8 or later, which addresses this stored XSS vulnerability.

Until the upgrade can be applied, restrict access to the Upload File Shares API to trusted and authenticated users only, minimizing the risk of malicious payload injection.

Additionally, review and harden Content Security Policy (CSP) settings to prevent execution of injected scripts, although the vulnerability bypasses default CSP protections.

Monitor activity logs for suspicious filenames and remove any malicious entries if found.

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