CVE-2002-0756 in Webmin
Summary
by MITRE
Cross-site scripting vulnerability in the authentication page for (1) Webmin 0.96 and (2) Usermin 0.90 allows remote attackers to insert script into an error page and possibly steal cookies.
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Analysis
by VulDB Data Team • 06/04/2019
The vulnerability described in CVE-2002-0756 represents a classic cross-site scripting flaw that specifically targets the authentication interfaces of Webmin and Usermin web-based management tools. This issue affects versions 0.96 of Webmin and 0.90 of Usermin, both of which are widely used for system administration through web interfaces. The vulnerability occurs within the authentication page where user input is not properly sanitized, creating an opportunity for malicious actors to inject arbitrary script code that can be executed in the context of authenticated users' browsers.
The technical exploitation of this vulnerability leverages the fact that error messages displayed on the authentication page do not adequately filter or escape user-supplied input. When an attacker crafts malicious input and submits it through the login form, the system processes this input without proper validation mechanisms, allowing script code to be embedded directly into error pages that are subsequently rendered to the user. This behavior directly violates security principles established in CWE-79, which addresses cross-site scripting vulnerabilities where untrusted data is improperly incorporated into web pages without adequate sanitization or encoding. The flaw essentially creates a persistent XSS vector that can be triggered during the authentication process when error conditions occur.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the capability to steal session cookies and potentially gain unauthorized access to administrative accounts. When users encounter error messages containing malicious scripts, their browsers execute the embedded code, which can include JavaScript designed to capture authentication cookies or redirect users to malicious sites. This makes the vulnerability particularly dangerous for administrative interfaces where users maintain elevated privileges. The attack can be executed remotely without requiring any special privileges or access to the system itself, making it a significant threat vector that aligns with ATT&CK technique T1566 for credential access through phishing and social engineering methods.
Mitigation strategies for this vulnerability should focus on input validation and output encoding practices that prevent script code from being executed in the browser context. System administrators should immediately upgrade to patched versions of Webmin and Usermin where available, as the vulnerability has been addressed in subsequent releases. Additionally, implementing proper content security policies and ensuring that all user input is properly sanitized before being displayed in error messages can prevent exploitation. Organizations should also consider deploying web application firewalls and monitoring for suspicious script injection attempts. The vulnerability demonstrates the critical importance of proper input validation in authentication systems and highlights how seemingly minor flaws in error handling can create significant security risks that compromise entire administrative environments.