Executive Summary

CVE-2023-53951 is a critical security vulnerability in Ever Gauzy version 0.281.9 where JSON Web Tokens (JWTs) are signed using a weak, predictable HMAC secret key. This weak key can be discovered by attackers intercepting normal requests, allowing them to forge valid JWTs. With these forged tokens, attackers can authenticate as privileged users, including administrators, and perform unauthorized actions by sending malicious API requests. The vulnerability stems from improper cryptographic signature verification due to the weak HMAC secret. [1, 3]

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Impact Analysis

This vulnerability can have severe impacts including unauthorized access to the system with administrative privileges. Attackers can bypass authentication, gain full control over the affected Ever Gauzy instance, and perform sensitive operations such as changing passwords or manipulating data. This leads to a high risk of data compromise, system integrity loss, and potential disruption of services. [1, 3]

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Detection Guidance

This vulnerability can be detected by intercepting and analyzing HTTP requests to identify JWT tokens signed with a weak or well-known HMAC secret key. Specifically, monitoring POST requests containing an 'Authorization: Bearer' token and testing the JWT signature strength can reveal the weakness. A practical detection method involves sending crafted HTTP GET requests to the '/api/auth/authenticated' endpoint with forged bearer tokens to check if unauthorized access is granted. Commands using tools like curl or HTTP clients to send such requests and inspect responses can be used. For example, sending a GET request with a forged JWT token in the Authorization header to '/api/auth/authenticated' can help detect if the system improperly accepts weakly signed tokens. [1]

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Mitigation Strategies

Immediate mitigation steps include replacing the weak or well-known HMAC secret key used for signing JWT tokens with a strong, randomly generated secret key to prevent attackers from forging tokens. Additionally, reviewing and updating the JWT authentication implementation to ensure proper cryptographic signature verification is critical. Restricting API access, monitoring for suspicious token usage, and applying patches or updates from the vendor that address this vulnerability are also recommended. [1, 3]

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