Timing Attack in Mojo::JWT Perl Library

Executive Summary

Mojo::JWT versions before 1.02 for Perl have a timing side-channel vulnerability in HMAC signature verification. The decode() method uses Perl's eq operator for comparison, which stops at the first differing byte. This causes the comparison time to vary based on matching leading bytes, allowing attackers to leak the secret signature through timing differences over multiple requests.

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Detection Guidance

To detect this vulnerability, check if your system uses Mojo::JWT versions before 1.02. Run: perl -MMojo::JWT -e 'print $Mojo::JWT::VERSION' to verify the installed version. If the output is less than 1.02, the system is vulnerable.

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Impact Analysis

An attacker could exploit this to recover the secret key used for signing tokens by measuring response times. Once the key is obtained, they can forge valid tokens and impersonate users or gain unauthorized access to systems relying on Mojo::JWT for authentication.

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Compliance Impact

This vulnerability could potentially violate compliance requirements under GDPR and HIPAA by exposing sensitive data through timing side-channel attacks. Attackers could exploit the timing variation to recover secret keys used for token verification, leading to unauthorized access to protected information.

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Mitigation Strategies

Upgrade Mojo::JWT to version 1.02 or later immediately. Use: cpan Mojo::JWT or cpanm Mojo::JWT to update the module. Ensure all dependent applications are restarted to apply the fix.

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