Authentication Bypass in FUXA via Path Traversal

Executive Summary

FUXA versions 1.3.1 and earlier have an authentication bypass vulnerability in their REST API. This happens because the API router does not properly normalize dot-segment sequences (like "/./" or "/../") in the URL path before applying authentication checks. As a result, attackers can craft requests with these dot-segments to access protected endpoints without providing valid credentials.

• For example, requests to paths such as /api/./users, /api/./roles, or /api/project/../users bypass authentication.

This flaw allows unauthorized users to retrieve sensitive user and role data from the system.

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Detection Guidance

This vulnerability can be detected by attempting to access protected REST API endpoints using dot-segment path prefixes that bypass authentication. For example, sending unauthenticated HTTP requests to paths such as /api/./users, /api/./roles, or /api/project/../users and checking if sensitive user or role data is returned without credentials indicates the presence of the vulnerability.

You can use command-line tools like curl to test for this vulnerability. Example commands include:

• curl -i http://<target-host>/api/./users
• curl -i http://<target-host>/api/./roles
• curl -i http://<target-host>/api/project/../users

If these requests return sensitive data without requiring authentication, the system is vulnerable.

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Impact Analysis

This vulnerability can have serious impacts because it allows attackers to bypass authentication and access sensitive information without any credentials.

• Unauthorized access to user and role data could lead to information disclosure.
• Attackers might gain insights into system users and permissions, potentially facilitating further attacks.

Overall, it compromises the confidentiality of sensitive data and the security of the system.

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Compliance Impact

The vulnerability allows unauthenticated access to protected endpoints, exposing sensitive user and role data without credentials.

Such unauthorized disclosure of sensitive information could potentially lead to non-compliance with data protection regulations like GDPR and HIPAA, which require strict access controls and protection of personal and sensitive data.

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Mitigation Strategies

Immediate mitigation steps include updating FUXA to a version later than 1.3.1 where this authentication bypass vulnerability is fixed.

If an update is not immediately possible, restrict access to the REST API endpoints by network controls such as firewalls or VPNs to limit exposure.

Additionally, monitor and log API requests for suspicious patterns involving dot-segment path sequences to detect potential exploitation attempts.

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