CVE-2016-7401 in Django
Summary
by MITRE
The cookie parsing code in Django before 1.8.15 and 1.9.x before 1.9.10, when used on a site with Google Analytics, allows remote attackers to bypass an intended CSRF protection mechanism by setting arbitrary cookies.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability described in CVE-2016-7401 represents a critical security flaw in the Django web framework that undermines the intended Cross-Site Request Forgery protection mechanisms. This issue affects Django versions prior to 1.8.15 and 1.9.x versions before 1.9.10, making it a widespread concern for applications that rely on Django's built-in security features. The flaw specifically manifests in the cookie parsing functionality that Django employs to handle user sessions and security tokens, creating a pathway for malicious actors to exploit the framework's CSRF protection system.
The technical root cause of this vulnerability lies in how Django processes cookies when they contain special characters or sequences that can be interpreted as multiple separate cookies. When Google Analytics or similar tracking services are integrated into a Django application, the presence of certain cookie values can trigger the framework's cookie parsing logic to incorrectly interpret a single cookie value as multiple distinct cookies. This misinterpretation allows attackers to inject malicious cookie values that bypass the CSRF protection checks, effectively rendering the security mechanism ineffective. The vulnerability operates at the application layer and can be exploited through carefully crafted cookie values that leverage the parsing inconsistencies in Django's cookie handling code.
The operational impact of CVE-2016-7401 is significant as it enables remote attackers to perform unauthorized actions on behalf of authenticated users without proper authorization checks. This vulnerability directly violates the principle of least privilege and can lead to various security breaches including session hijacking, unauthorized data modifications, and privilege escalation attacks. The attack vector is particularly concerning because it can be executed through standard web browser interactions without requiring special tools or conditions beyond the presence of the vulnerable Django version and Google Analytics integration. Security researchers have classified this as a medium to high severity vulnerability due to its potential for bypassing critical security controls and the relatively straightforward nature of the attack.
Organizations affected by this vulnerability should immediately upgrade to Django versions 1.8.15 or 1.9.10, which contain the necessary patches to address the cookie parsing issue. The mitigation strategy involves not only updating the Django framework but also reviewing all applications that utilize Google Analytics or similar tracking services to ensure proper cookie handling. Security teams should implement additional monitoring for suspicious cookie patterns and consider implementing custom cookie validation mechanisms as a defensive measure. This vulnerability aligns with CWE-20, which addresses improper input validation, and maps to ATT&CK technique T1213, focusing on data from information repositories, as it allows unauthorized access to protected resources through manipulated session data. The incident highlights the importance of thorough input validation and the potential security implications of third-party service integrations within web applications.