CVE-2020-15906 in Tiki
Summary
by MITRE • 10/23/2020
tiki-login.php in Tiki before 21.2 sets the admin password to a blank value after 50 invalid login attempts.
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Analysis
by VulDB Data Team • 11/26/2020
This vulnerability exists in the Tiki content management system where the login authentication mechanism fails to properly handle excessive failed login attempts. The flaw manifests in the tiki-login.php script which implements a security counter that tracks invalid login attempts and subsequently resets the administrator password to a blank value after exactly fifty failed authentication attempts. This represents a critical security weakness that directly undermines the system's authentication integrity and creates an unintended access vector.
The technical implementation of this vulnerability stems from improper session management and authentication state handling within the Tiki application. When the system reaches the threshold of fifty invalid login attempts, it automatically nullifies the administrator account's password field, effectively removing the authentication barrier that protects administrative access. This behavior creates a race condition between legitimate administrators and potential attackers, as the system's own security mechanism inadvertently enables unauthorized access to administrative functions. The vulnerability operates at the application layer and affects the authentication subsystem, making it a direct violation of secure authentication practices.
The operational impact of this vulnerability is severe as it fundamentally compromises the security posture of any Tiki installation that has been subjected to fifty or more failed login attempts. An attacker who successfully triggers this condition gains complete administrative access to the system without requiring any additional credentials or exploitation techniques. This creates a scenario where legitimate administrators may inadvertently lock themselves out of their own systems while simultaneously providing a clear path for unauthorized access. The vulnerability affects all versions prior to 21.2 and represents a design flaw that contradicts established security principles for authentication management and account lockout mechanisms.
Security standards such as CWE-307 and CWE-308 directly relate to this vulnerability, as it demonstrates improper handling of authentication attempts and weak session management practices. The ATT&CK framework categorizes this under T1110.003 - Credential Access: Password Policy Violations, as it creates a condition where password security is undermined by system-level automatic resets. Additionally, this vulnerability aligns with T1078.004 - Valid Accounts: Default Accounts, as the blank password effectively creates a default account state that bypasses normal authentication requirements. Organizations using affected Tiki versions should immediately apply the patch released in version 21.2 to prevent exploitation of this authentication bypass mechanism.
Mitigation strategies include implementing proper account lockout mechanisms that require administrator intervention rather than automatic password resets, configuring additional authentication layers such as multi-factor authentication, and monitoring login attempt patterns for suspicious activity. Network segmentation and intrusion detection systems should be deployed to monitor for potential exploitation attempts, while administrators should establish clear procedures for handling account lockout scenarios. The patch for this vulnerability specifically addresses the authentication flow to prevent automatic password clearing and instead implements proper account lockout procedures that require manual administrative intervention to restore access.