CVE-2021-41930 in Online Covid Vaccination Scheduler System
Summary
by MITRE • 01/24/2022
Cross site scripting (XSS) vulnerability in Sourcecodester Online Covid Vaccination Scheduler System v1 by oretnom23, allows attackers to execute arbitrary code via the lid parameter to /scheduler/addSchedule.php.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 01/28/2022
The CVE-2021-41930 vulnerability represents a critical cross site scripting flaw within the Sourcecodester Online Covid Vaccination Scheduler System version 1, developed by oretnom23. This vulnerability resides in the application's handling of user input parameters, specifically the lid parameter within the /scheduler/addSchedule.php endpoint. The flaw enables malicious actors to inject malicious scripts into the web application's response, potentially compromising user sessions and data integrity. The vulnerability classification aligns with CWE-79 which defines cross site scripting as a weakness where untrusted data is sent to a web browser without proper validation or escaping, allowing attackers to execute arbitrary scripts in the victim's browser context.
The technical exploitation of this vulnerability occurs when an attacker manipulates the lid parameter to inject malicious javascript code into the scheduler application. When the application processes this parameter without adequate input sanitization or output encoding, the injected script becomes part of the page's HTML response. This allows attackers to perform session hijacking, steal cookies, redirect users to malicious sites, or even execute arbitrary commands on the victim's browser. The vulnerability demonstrates poor input validation practices and inadequate output encoding mechanisms that are fundamental security controls in web application development. According to ATT&CK framework, this vulnerability maps to T1566.001 which covers "Phishing: Spearphishing Attachment" and T1584.001 which involves "Compromise of Third-Party Applications" as attackers can exploit this flaw to gain unauthorized access to sensitive vaccination scheduling data.
The operational impact of this vulnerability extends beyond simple script execution, as it can lead to complete compromise of the vaccination scheduling system's integrity and confidentiality. Attackers could manipulate vaccination records, impersonate authorized users, or gain access to sensitive personal health information of individuals scheduled for vaccination. The vulnerability affects the entire user base that interacts with the scheduler application, potentially compromising thousands of vaccination appointments and personal data entries. Organizations relying on this system face significant risks including data breaches, compliance violations under healthcare privacy regulations, and potential legal consequences. The vulnerability also undermines public trust in digital health infrastructure, especially during critical pandemic response scenarios where such systems are essential for coordinating vaccination efforts.
Mitigation strategies for CVE-2021-41930 must address both immediate remediation and long-term security improvements. The primary fix involves implementing proper input validation and output encoding mechanisms throughout the application's codebase, specifically ensuring that all user-supplied parameters including the lid parameter are sanitized before being processed or displayed. Developers should implement context-specific output encoding, using appropriate escaping mechanisms for different contexts such as HTML, JavaScript, and URL contexts. Additionally, the system should employ parameterized queries and input validation routines to prevent malicious data from being processed. Organizations should also implement web application firewalls to detect and block suspicious parameter values, conduct regular security code reviews, and establish secure coding practices. The remediation aligns with OWASP Top 10 recommendations for preventing XSS vulnerabilities and should be complemented by regular penetration testing and vulnerability scanning to ensure comprehensive protection against similar threats.