Executive Summary

OpenBullet2 version 0.3.2 and earlier contains a critical authentication bypass vulnerability in its API key authentication middleware.

This vulnerability allows unauthenticated attackers to gain administrative access by sending an empty X-Api-Key header value.

The root cause is that the middleware compares the provided X-Api-Key header against an empty default AdminApiKey string, which mistakenly grants access when the header is empty.

As a result, attackers can access the admin console and all API endpoints without valid credentials.

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Impact Analysis

This vulnerability can have a severe impact because it allows attackers to bypass authentication and gain full administrative access.

With admin access, attackers can control the application, access sensitive data, modify configurations, and potentially disrupt services.

The vulnerability has a high severity rating with a CVSS score of 9.3, indicating it is highly exploitable and can cause significant damage.

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Detection Guidance

This vulnerability can be detected by monitoring API requests to the OpenBullet2 server for the presence of an empty X-Api-Key header value. Specifically, any request that includes an X-Api-Key header with no value should be flagged as suspicious because it may indicate an attempt to bypass authentication.

To detect such attempts on your system or network, you can use network traffic inspection tools or web server logs to filter requests with an empty X-Api-Key header.

• Using command-line tools like tcpdump or tshark to capture HTTP headers and filter for empty X-Api-Key headers.
• Example tshark command to filter HTTP requests with empty X-Api-Key header: tshark -Y 'http.header.x-api-key == ""' -T fields -e ip.src -e http.host -e http.request.uri
• Alternatively, grep your web server access logs for requests containing 'X-Api-Key:' with no value following it.

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Mitigation Strategies

Immediate mitigation steps include updating OpenBullet2 to a version later than 0.3.2 where this authentication bypass vulnerability is fixed.

If an update is not immediately possible, you should implement network-level controls to block or monitor requests with empty X-Api-Key headers to prevent unauthorized access.

Additionally, review and harden API key authentication middleware to ensure that empty or missing API keys are properly rejected and do not default to an empty string comparison.

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Compliance Impact

The vulnerability allows unauthenticated attackers to gain administrative access to OpenBullet2, potentially exposing sensitive data and administrative functions without proper authorization.

Such unauthorized access could lead to violations of compliance requirements in standards and regulations like GDPR and HIPAA, which mandate strict access controls and protection of sensitive information.

By bypassing authentication, this flaw undermines the security controls necessary to ensure confidentiality, integrity, and accountability, which are core principles in these regulations.

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