CVE-2020-24313 in Ultimate Appointment Booking
Summary
by MITRE
Etoile Web Design Ultimate Appointment Booking & Scheduling WordPress Plugin v1.1.9 and lower does not sanitize the value of the "Appointment_ID" GET parameter before echoing it back out inside an input tag. This results in a reflected XSS vulnerability that attackers can exploit with a specially crafted URL.
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Analysis
by VulDB Data Team • 08/26/2020
The vulnerability identified as CVE-2020-24313 affects the Etoile Web Design Ultimate Appointment Booking & Scheduling WordPress plugin version 1.1.9 and earlier, representing a critical security flaw that exposes users to reflected cross-site scripting attacks. This issue stems from inadequate input validation and sanitization practices within the plugin's codebase, specifically when processing the Appointment_ID GET parameter. The vulnerability manifests when the plugin fails to properly sanitize user-supplied data before incorporating it into HTML output, creating an avenue for malicious actors to inject harmful scripts into web pages viewed by unsuspecting users. The flaw exists within the plugin's handling of appointment identifiers passed through URL parameters, where the system directly echoes the unsanitized input value into an HTML input tag without appropriate security measures.
From a technical perspective, this vulnerability operates as a reflected cross-site scripting attack where malicious payloads are embedded within the Appointment_ID parameter of a URL. When a victim clicks on a crafted link containing malicious script code within the Appointment_ID value, the plugin processes this input without proper sanitization and subsequently reflects the malicious code back to the user's browser within the input field. The vulnerability is classified under CWE-79 as a failure to sanitize or incorrectly sanitizing user-provided data before incorporating it into a web page, which directly enables XSS attacks. The attack vector is particularly concerning because it requires minimal user interaction beyond clicking a malicious link, making it highly exploitable in phishing campaigns or social engineering attacks. The reflected nature of the vulnerability means that the malicious script is not stored on the server but is instead reflected back to the user's browser from the web application's response, making it difficult to detect through traditional server-side scanning methods.
The operational impact of this vulnerability extends beyond simple script injection, potentially allowing attackers to perform session hijacking, steal sensitive user information, manipulate web page content, or redirect users to malicious websites. The reflected XSS attack can be leveraged to bypass the same-origin policy that normally protects web browsers, enabling attackers to access cookies, session tokens, or other sensitive data that may be stored in the victim's browser. In a WordPress environment, this vulnerability could potentially be exploited to gain unauthorized access to administrative functions, especially if the victim is logged in as an administrator or has elevated privileges. The attack can be particularly damaging in business environments where appointment booking systems handle sensitive customer data, potentially exposing personal information, medical records, or financial details that users trust to remain secure. The vulnerability also creates opportunities for attackers to deface websites, inject malicious advertisements, or establish persistent backdoors through more sophisticated attack chains that may follow initial XSS exploitation.
Organizations should immediately implement multiple layers of defense to mitigate this vulnerability, beginning with the immediate upgrade to the latest version of the plugin where the sanitization issue has been addressed. The recommended remediation strategy includes implementing proper input validation and output encoding mechanisms that ensure all user-supplied data is sanitized before being processed or displayed. Security measures should incorporate Content Security Policy (CSP) headers to prevent unauthorized script execution, and regular security audits should be conducted to identify similar vulnerabilities in other plugins or themes. The mitigation approach should align with ATT&CK framework techniques related to defense evasion and credential access, as reflected XSS vulnerabilities can serve as entry points for more comprehensive attacks. Additionally, implementing web application firewalls and monitoring for suspicious URL patterns containing encoded script payloads can provide additional protection layers. Organizations should also consider implementing user education programs to raise awareness about the dangers of clicking untrusted links, as social engineering remains a primary attack vector for exploiting such vulnerabilities. The security posture should include regular patch management processes and vulnerability scanning to ensure that all WordPress plugins and themes remain up to date with the latest security fixes, as this vulnerability demonstrates the critical importance of maintaining current software versions to prevent exploitation of known security flaws.