CVE-2011-4140 in Django
Summary
by MITRE
The CSRF protection mechanism in Django through 1.2.7 and 1.3.x through 1.3.1 does not properly handle web-server configurations supporting arbitrary HTTP Host headers, which allows remote attackers to trigger unauthenticated forged requests via vectors involving a DNS CNAME record and a web page containing JavaScript code.
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Analysis
by VulDB Data Team • 11/24/2021
The vulnerability identified as CVE-2011-4140 represents a critical weakness in Django's cross-site request forgery protection system, affecting versions through 1.2.7 and 1.3.x up to 1.3.1. This flaw stems from Django's inadequate handling of HTTP Host headers when web servers support arbitrary header values, creating a pathway for attackers to bypass security measures that should prevent unauthorized actions. The vulnerability specifically exploits the trust relationship between Django applications and their web server configurations, particularly when those servers accept and process custom Host headers that may not align with the application's expected domain boundaries.
The technical implementation of this vulnerability relies on the improper validation of HTTP Host headers within Django's CSRF protection framework. When web servers accept arbitrary Host headers, Django's validation logic fails to properly verify that the Host header matches the expected domain configuration, allowing malicious actors to craft forged requests that appear legitimate to the application. This occurs because the CSRF protection mechanism depends on the Host header to establish trust boundaries, but when that header can be manipulated through DNS CNAME records, attackers can create scenarios where their malicious requests are accepted as valid by the application's security controls. The flaw operates at the intersection of web server configuration flexibility and application-level security assumptions, creating an exploitable gap in the authentication flow.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it allows remote attackers to execute unauthorized actions on behalf of authenticated users within the Django application. Attackers can leverage this weakness by creating malicious web pages containing JavaScript code that triggers forged requests to the vulnerable Django application, potentially enabling data modification, user account manipulation, or other unauthorized operations. The attack vector specifically involves DNS CNAME records that can be manipulated to point to the target application, combined with JavaScript execution that can submit requests with forged Host headers. This combination allows attackers to bypass the CSRF protection entirely, as the application's security checks fail to properly validate the request origins due to the malleable Host header handling.
Organizations using affected Django versions should immediately implement mitigations including upgrading to patched versions where available, configuring web servers to reject arbitrary Host headers, and implementing additional validation layers beyond the default CSRF protection mechanisms. The vulnerability aligns with CWE-346, which addresses "Improper Verification of Cryptographic Signature", as it involves the improper verification of request authenticity through header validation. From an ATT&CK framework perspective, this vulnerability maps to techniques involving credential access and privilege escalation through web application exploitation, specifically targeting the application layer security controls that should prevent unauthorized operations. Security teams should also consider implementing network-level controls to monitor and restrict Host header values, as well as conducting thorough security assessments of web server configurations to ensure they properly enforce domain boundaries and do not allow arbitrary header manipulation that could compromise application security.