CVE-2019-14537 in YOURLS
Summary
by MITRE
YOURLS through 1.7.3 is affected by a type juggling vulnerability in the api component that can result in login bypass.
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Analysis
by VulDB Data Team • 11/21/2023
The vulnerability identified as CVE-2019-14537 affects YOURLS version 1.7.3 and earlier, representing a critical type juggling flaw within the application's API component that enables unauthorized access. This vulnerability specifically targets the authentication mechanism of the YOURLS URL shortening platform, which is widely used for creating custom short URLs and managing link redirections. The issue stems from how the application handles input validation during the authentication process, creating a pathway for malicious actors to bypass the standard login procedures without proper credentials.
The technical flaw manifests through PHP's type juggling behavior where certain input comparisons do not properly enforce data types, allowing attackers to manipulate authentication parameters. When legitimate users attempt to log in, the system performs comparisons between user-provided credentials and stored values that are susceptible to type coercion attacks. This vulnerability falls under the CWE-707 category of improper neutralization of input during web application processing, specifically relating to weak input validation and type handling. The attack vector exploits the fact that PHP's loose comparison operators can produce unexpected results when comparing different data types, enabling attackers to craft inputs that satisfy authentication checks despite not providing valid credentials.
The operational impact of this vulnerability is severe as it allows unauthorized users to gain administrative access to YOURLS installations without legitimate credentials. This bypass enables attackers to manipulate the URL shortening service by adding, modifying, or deleting short URLs, potentially redirecting users to malicious destinations. The vulnerability affects all installations running YOURLS versions up to and including 1.7.3, making it particularly concerning given the widespread adoption of this platform for both personal and enterprise use. Attackers could leverage this vulnerability to create phishing campaigns, distribute malware through malicious redirects, or simply disrupt the service by modifying or deleting existing links. The implications extend beyond simple unauthorized access as the compromised system could serve as a pivot point for further attacks within the network infrastructure.
Security mitigations for this vulnerability primarily involve immediate upgrading to YOURLS version 1.7.4 or later, which contains the necessary patches to address the type juggling issue. Organizations should also implement additional security measures such as restricting API access through network firewalls, implementing rate limiting on authentication attempts, and monitoring for suspicious login patterns. The remediation process should include thorough testing of the updated system to ensure that all API endpoints function correctly and that the authentication mechanism properly validates input types. Security teams should also review access controls and implement principle of least privilege for API users, ensuring that only authorized personnel have administrative access to the YOURLS installation. Additionally, the vulnerability demonstrates the importance of following secure coding practices, particularly in handling user input and implementing proper type checking in web applications, as outlined in the OWASP Top Ten and MITRE ATT&CK framework's application security categories.