CVE-2004-0294 in YaBB
Summary
by MITRE
YaBB 1 SP 1.3.1 displays different error messages when a user exists or not, which makes it easier for remote attackers to identify valid users and conduct a brute force password guessing attack.
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Analysis
by VulDB Data Team • 07/13/2025
The vulnerability identified as CVE-2004-0294 affects YaBB 1 SP 1.3.1 bulletin board software, presenting a significant security weakness through its inconsistent error handling mechanisms. This flaw resides in the authentication system where the application provides different error responses depending on whether a username exists in the system. The vulnerability stems from the application's failure to implement consistent error messaging for all authentication attempts, creating a predictable pattern that adversaries can exploit to determine valid user accounts.
This security weakness directly maps to CWE-209, which addresses the issue of information exposure through error messages that reveal system state or configuration details. The vulnerability enables attackers to perform user enumeration attacks by observing the different error messages returned when attempting to authenticate with various usernames. When a user enters a non-existent username, the system returns one type of error message, while entering a valid username but incorrect password produces a different response. This differential response pattern allows malicious actors to systematically test usernames and identify valid accounts without needing to know the actual passwords.
The operational impact of this vulnerability extends beyond simple user enumeration, as it significantly facilitates brute force password guessing attacks. Attackers can leverage the predictable error responses to build lists of valid usernames and then focus their password guessing efforts on these identified accounts, dramatically reducing the time and computational resources required to compromise user accounts. This vulnerability effectively undermines the security model of the authentication system by providing attackers with information that should remain confidential during the authentication process.
The attack vector for this vulnerability is entirely remote, making it particularly dangerous as it requires no local system access or physical presence. An attacker can exploit this vulnerability through network-based interactions with the web application, using automated tools to rapidly test username combinations and observe the system's responses. This aligns with ATT&CK technique T1110, which covers credential access through brute force methods, where the ability to enumerate valid users provides a significant advantage in executing successful password guessing campaigns.
Mitigation strategies for this vulnerability involve implementing consistent error handling throughout the authentication process. The application should return identical error messages regardless of whether the username exists or not, ensuring that all authentication attempts produce the same response format. This approach prevents attackers from distinguishing between valid and invalid usernames through error message analysis. Additionally, implementing account lockout mechanisms, rate limiting, and CAPTCHA verification can further reduce the effectiveness of brute force attacks. The most effective solution involves updating to a newer version of YaBB software that addresses this specific vulnerability, as the developers have likely implemented proper error handling and authentication mechanisms in subsequent releases. Organizations should also consider implementing multi-factor authentication and robust monitoring systems to detect and respond to suspicious authentication attempts that may indicate exploitation of this vulnerability.