CVE-2009-5015 in TurboGears2
Summary
by MITRE
The URL dispatch mechanism in TurboGears2 (aka tg2) before 2.0.2 exposes controller methods even when an @expose decoration is not used, which has unspecified impact and attack vectors.
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Analysis
by VulDB Data Team • 02/08/2019
The vulnerability identified as CVE-2009-5015 affects TurboGears2 version 2.0.1 and earlier, specifically targeting the URL dispatch mechanism that governs how web application routes are handled. This flaw represents a significant security weakness in the framework's access control implementation where the system fails to properly restrict access to controller methods that should be protected from direct URL invocation. The issue stems from the framework's inability to distinguish between methods that are intended to be publicly accessible and those that should remain hidden from direct web access, creating a potential pathway for unauthorized system interactions.
The technical flaw manifests in the URL dispatch system's design where controller methods are automatically exposed through the web interface regardless of whether they have been explicitly decorated with the @expose decorator. This behavior creates an unintended attack surface where any method within a controller class becomes accessible via direct URL requests, bypassing the normal access control mechanisms that should govern such interactions. The vulnerability essentially allows for privilege escalation through direct method invocation, as the framework does not properly validate whether a given method should be accessible through the web interface.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially enable attackers to execute arbitrary code or manipulate application state through direct method calls. The unspecified nature of the impact and attack vectors suggests that this vulnerability could be exploited in multiple ways depending on the application's specific implementation, potentially allowing for data manipulation, unauthorized access to sensitive functions, or even complete system compromise. The attack surface expands significantly since any controller method can be called directly, potentially exposing internal application functions that were never intended to be publicly accessible.
This vulnerability aligns with CWE-284, which addresses improper access control mechanisms, and represents a clear violation of the principle of least privilege in web application security. The flaw also maps to ATT&CK technique T1210, which involves exploiting weaknesses in remote services, as it allows for unauthorized access to application functionality through web-based attack vectors. The vulnerability demonstrates poor security by design in the framework's architecture, where the default behavior of exposing all controller methods creates an inherent security risk that requires explicit mitigation through proper decorator usage.
Organizations using TurboGears2 versions prior to 2.0.2 should immediately upgrade to version 2.0.2 or later to address this vulnerability. The recommended mitigation strategy involves implementing proper access control measures through the use of @expose decorators on all controller methods and ensuring that only explicitly intended methods are accessible through the web interface. Additionally, security reviews should be conducted to identify any methods that may have been inadvertently exposed due to missing decorators, and the application architecture should be reviewed to ensure that the principle of least privilege is properly implemented. Network segmentation and web application firewalls can provide additional layers of protection while the framework is being updated to a secure version.