CVE-2021-46558 in PBX
Summary
by MITRE • 02/15/2022
Multiple cross-site scripting (XSS) vulnerabilities in the Add User module of Issabel PBX 20200102 allows attackers to execute arbitrary web scripts or HTML via a crafted payload inserted into the username and password fields.
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Analysis
by VulDB Data Team • 02/18/2022
The vulnerability CVE-2021-46558 represents a critical cross-site scripting flaw discovered in the Add User module of Issabel PBX version 20200102, a widely used open-source unified communications platform. This vulnerability resides within the user management functionality of the system, specifically in how the application processes and validates input data submitted through the username and password fields during user creation operations. The issue stems from insufficient sanitization and validation of user-supplied input, creating a pathway for malicious actors to inject malicious scripts that can execute within the context of other users' browsers. The affected system operates under the assumption that user input is trustworthy, failing to properly encode or escape special characters that could be interpreted as executable code by web browsers, thereby exposing the entire communication infrastructure to potential exploitation.
The technical implementation of this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications. Attackers can leverage this weakness by crafting malicious payloads containing script tags or other executable code within the username and password fields during user registration or modification processes. When the system displays these user inputs in web interfaces without proper sanitization, the embedded scripts execute in the browsers of other users who view the affected pages. This allows adversaries to perform various malicious activities including session hijacking, credential theft, data exfiltration, and potentially gaining elevated privileges within the system. The vulnerability's impact is amplified because the Add User module is frequently accessed by administrators and legitimate users, providing multiple potential attack vectors for exploitation. The XSS flaw operates at the application layer, targeting the web interface components that render user information and can be exploited through both reflected and stored XSS mechanisms.
The operational impact of CVE-2021-46558 extends beyond simple script execution, presenting significant risks to the overall security posture of Issabel PBX deployments. An attacker who successfully exploits this vulnerability can establish persistent access to the communication platform, potentially compromising all user sessions and sensitive telephony data. The attack surface includes not only the direct execution of malicious scripts but also the potential for more sophisticated attacks such as phishing campaigns that can trick users into revealing confidential information. The vulnerability affects the integrity and confidentiality of the system's user management functions, potentially enabling unauthorized access to voice mail systems, call logs, and other critical telephony features. Organizations relying on Issabel PBX for business communications face substantial risk of data breaches and service disruption, particularly in environments where the system handles sensitive customer information or operates in regulated industries requiring strict compliance with data protection standards.
Mitigation strategies for CVE-2021-46558 must address both immediate remediation and long-term security hardening measures. The primary solution involves implementing proper input validation and output encoding mechanisms throughout the Add User module, ensuring that all user-supplied data is sanitized before being stored or displayed. This includes applying strict validation rules for username and password fields, implementing proper HTML entity encoding for all displayed user content, and utilizing content security policies to prevent unauthorized script execution. Organizations should also consider implementing web application firewalls to detect and block malicious payloads attempting to exploit XSS vulnerabilities. Regular security updates and patches should be applied immediately upon availability, with system administrators monitoring for any signs of exploitation attempts. The remediation process should include comprehensive testing to ensure that the fixes do not introduce regressions in legitimate functionality while maintaining the system's operational integrity. Additionally, implementing security awareness training for administrators and users can help identify potential exploitation attempts and reduce the likelihood of successful attacks. The vulnerability underscores the importance of following secure coding practices and adhering to established security frameworks such as the OWASP Top Ten and NIST cybersecurity guidelines to prevent similar issues in future development cycles.