CVE-2015-6961 in Web2py
Summary
by MITRE
Open redirect vulnerability in gluon/tools.py in Web2py 2.9.11 allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a URL in the _next parameter to user/logout.
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Analysis
by VulDB Data Team • 01/04/2023
The CVE-2015-6961 vulnerability represents a critical open redirect flaw discovered in the Web2py framework version 2.9.11 within the gluon/tools.py module. This vulnerability specifically affects the user logout functionality where the application fails to properly validate or sanitize the _next parameter before using it for redirection. The flaw enables remote attackers to craft malicious URLs that redirect users from legitimate web applications to attacker-controlled websites, creating a significant security risk for organizations relying on this framework. The vulnerability is particularly concerning because it leverages a common authentication flow that users frequently interact with, making it an ideal vector for social engineering and phishing attacks.
The technical implementation of this vulnerability stems from inadequate input validation within the Web2py framework's authentication handling mechanism. When a user accesses the user/logout endpoint with a _next parameter containing a malicious URL, the application processes this parameter without proper sanitization or domain verification checks. This allows attackers to specify any arbitrary URL in the _next parameter, which the framework then uses to redirect users upon successful logout. The flaw exists at the application logic level where the framework assumes all redirect targets are legitimate and trustworthy, failing to implement proper validation of the destination URLs against a whitelist of approved domains or implementing proper URL scheme and host validation.
The operational impact of this vulnerability extends beyond simple redirection, creating a substantial risk for organizations using Web2py 2.9.11 in production environments. Attackers can exploit this flaw to redirect users to phishing sites that mimic legitimate corporate portals, financial institutions, or service providers, potentially capturing sensitive credentials, personal information, or financial data. The vulnerability is particularly dangerous in enterprise environments where users may be directed to logout pages from various trusted applications, making the redirection appear legitimate to end users. This type of attack can result in significant financial losses, data breaches, and reputational damage to organizations that fail to address this vulnerability promptly.
Organizations should implement immediate mitigations including upgrading to Web2py versions that have addressed this vulnerability, typically those released after the patching cycle in 2015. The fix involves implementing proper input validation and sanitization of the _next parameter, ensuring that any redirect URLs are either validated against a whitelist of approved domains or properly sanitized to prevent malicious URL injection. Security teams should also consider implementing additional controls such as domain-based access controls, monitoring for suspicious redirect patterns, and user education about recognizing potential phishing attempts. From a cybersecurity framework perspective, this vulnerability aligns with CWE-601 Open Redirect and maps to attack techniques in the MITRE ATT&CK framework under the T1566 Phishing category, specifically targeting credential theft through malicious redirects. Organizations should also consider implementing web application firewalls and network monitoring solutions to detect and block suspicious redirect traffic patterns that may indicate exploitation attempts.