CVE-2018-13060 in Easy!Appointments
Summary
by MITRE
Easy!Appointments 1.3.0 has a Guessable CAPTCHA issue.
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Analysis
by VulDB Data Team • 04/16/2024
The vulnerability CVE-2018-13060 identifies a significant security flaw in Easy!Appointments version 1.3.0 where the CAPTCHA implementation suffers from guessability issues that undermine its effectiveness as a security control. This weakness allows attackers to bypass the CAPTCHA protection mechanism that is typically designed to prevent automated attacks and spam submissions. The vulnerability stems from insufficient entropy and predictable patterns in the CAPTCHA generation algorithm, making it susceptible to automated guessing or brute force attempts that can successfully authenticate malicious requests without proper human verification.
This vulnerability falls under the broader category of weak authentication mechanisms and represents a specific implementation flaw that can be categorized as a CWE-310 weakness related to cryptographic issues. The predictable nature of the CAPTCHA makes it vulnerable to machine learning based attacks and automated bots that can analyze patterns and successfully bypass the security measure. From an operational perspective, this weakness directly impacts the system's ability to distinguish between legitimate users and automated malicious actors, potentially allowing for account takeover attempts, spam submissions, and denial of service attacks against the appointment booking system.
The attack surface for this vulnerability extends beyond simple spam prevention to include more serious security implications such as credential stuffing attacks, automated service abuse, and potential exploitation of other system weaknesses. According to ATT&CK framework, this vulnerability maps to T1110.003 (Brute Force) and T1078.004 (Valid Accounts) as attackers can leverage the bypassed CAPTCHA to conduct more sophisticated attacks. The impact is particularly concerning for web applications that handle sensitive user data and appointment scheduling information, as successful exploitation could lead to unauthorized access to personal schedules, appointment manipulation, and potential data breaches.
Organizations using Easy!Appointments 1.3.0 should immediately implement mitigations including upgrading to a patched version that employs cryptographically secure CAPTCHA generation methods with sufficient entropy. The recommended approach involves replacing the existing CAPTCHA implementation with one that uses randomized character sets, varying font styles, and noise injection techniques to prevent pattern recognition. Additionally, implementing rate limiting and request monitoring can help detect and block automated attack patterns. Security teams should also consider implementing multi-factor authentication mechanisms as additional layers of protection beyond CAPTCHA, and conduct regular security assessments to identify similar weaknesses in other authentication mechanisms throughout the application stack.