The security threat concerns a reflected Cross-Site Scripting (XSS) vulnerability in RosarioSIS version 6.7.2, identified as CVE-2020-15718. RosarioSIS is an open-source school information system widely used for managing student data, schedules, and administrative tasks. The vulnerability arises from insufficient sanitization of the 'include_inactive' parameter in the Scheduling module's PrintSchedules.php page. An attacker with administrative privileges can craft a malicious URL embedding JavaScript code that is reflected and executed in the victim's browser when the URL is accessed. The provided proof-of-concept demonstrates injecting an 'onmouseover' event handler that triggers a JavaScript alert, confirming the XSS flaw. Exploitation requires the attacker to be logged in as an admin user and to trick the victim into clicking the malicious link, indicating user interaction is necessary. Although no official patch links are provided, the availability of exploit code lowers the barrier for attackers. The impact includes potential session hijacking, theft of sensitive information, and execution of arbitrary actions with admin privileges. The vulnerability affects the web interface accessed via browsers and has been tested on Windows environments. Organizations should check the vendor's repository for updates or apply input validation and output encoding as interim mitigations.

For European organizations, especially educational institutions using RosarioSIS, this vulnerability threatens the confidentiality and integrity of sensitive student and administrative data. Successful exploitation could allow attackers to hijack administrator sessions, manipulate schedules, or access private information, potentially leading to unauthorized data disclosure and administrative disruption. Although exploitation requires administrative credentials and user interaction, phishing or social engineering attacks could facilitate this. The resulting disruption could damage institutional reputation and trust. Given RosarioSIS's adoption in several European countries, the impact could be significant within the education sector. Additionally, compromised admin accounts could serve as a foothold for further network attacks, increasing overall organizational risk.

1. Verify and apply any available vendor patches or updates for RosarioSIS beyond version 6.7.2 immediately. 2. If no patch exists, implement strict input validation and output encoding on all user-supplied parameters, especially 'include_inactive' in the Scheduling module, to neutralize script injection. 3. Deploy Content Security Policy (CSP) headers to restrict execution of unauthorized scripts within the application context. 4. Enforce multi-factor authentication (MFA) for all administrative accounts and restrict admin access to trusted networks to reduce credential compromise risk. 5. Conduct targeted training for administrators on phishing and social engineering to prevent inadvertent clicking of malicious links. 6. Monitor web server logs for suspicious URL patterns indicative of XSS attempts. 7. Deploy Web Application Firewalls (WAF) with rules tailored to detect and block reflected XSS payloads targeting RosarioSIS. 8. Regularly audit user privileges to ensure only necessary users hold administrative rights. 9. Isolate the RosarioSIS application environment to limit lateral movement if a compromise occurs.