H3 Timing Side-Channel Vulnerability in Basic Authentication

A timing side-channel vulnerability has been identified in the H3 framework, specifically in versions 2.0.1-beta.0 through 2.0.0-rc.8. The issue arises in the 'requireBasicAuth' function, where unsafe string comparison is used. This vulnerability allows attackers to deduce valid password characters one at a time by measuring response times, effectively bypassing password complexity requirements. The vulnerability is exploitable in local networks or cloud environments where the attacker shares network space with the target.

Impact

Exploitation of this vulnerability allows remote attackers to recover passwords, reducing the complexity of cracking a password from exponential to linear by guessing one character at a time.

Reproduction

To reproduce this vulnerability, send two concurrent requests to the server. Packet A should contain an incorrect password starting with a known wrong character, while Packet B should include a guessed character. By analyzing the response times, it's possible to determine the correct password character by character. This method is particularly effective in local or cloud environments where the attacker is co-located with the target.

Remediation

Users can upgrade to H3 version 2.0.1-rc.9 to address this vulnerability.