CVE-2012-4520 in django
Summary
by MITRE
The django.http.HttpRequest.get_host function in Django 1.3.x before 1.3.4 and 1.4.x before 1.4.2 allows remote attackers to generate and display arbitrary URLs via crafted username and password Host header values.
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Analysis
by VulDB Data Team • 12/20/2021
The vulnerability identified as CVE-2012-4520 affects the Django web framework's HttpRequest.get_host function implementation in versions prior to 1.3.4 and 1.4.2. This flaw resides in the framework's handling of HTTP Host headers during request processing, specifically when parsing username and password credentials within these headers. The issue stems from inadequate validation and sanitization of Host header values, creating a potential path for malicious actors to manipulate URL generation within Django applications. The vulnerability is categorized under CWE-20, which represents improper input validation, and aligns with ATT&CK technique T1190 for exploiting vulnerabilities in web applications.
The technical exploitation occurs when attackers craft malicious Host headers containing username and password credentials that are then processed by Django's get_host function. This function, designed to extract the host portion of a request, fails to properly sanitize these credential values before using them in URL construction. When Django applications utilize the get_host result for generating absolute URLs, redirects, or other location-based operations, the malicious credentials can be embedded into the generated URLs. This creates a scenario where attackers can influence the content of URLs displayed to end users or used in application logic, potentially enabling phishing attacks, cross-site scripting, or other malicious activities.
The operational impact of this vulnerability extends beyond simple URL manipulation, as it can compromise the integrity of Django applications that rely on proper host validation for security decisions. Applications using Django's built-in URL generation mechanisms, particularly those implementing authentication flows, session management, or redirect functionalities, become susceptible to manipulation. The vulnerability affects not only direct URL generation but also any application logic that depends on the host information extracted from HTTP headers. Attackers can leverage this to construct misleading URLs that appear legitimate to users, potentially bypassing security measures that depend on host validation or creating confusion in applications that process these URLs for further operations.
Organizations using affected Django versions should immediately apply the security patches released by the Django project to address this vulnerability. The recommended mitigation strategy involves upgrading to Django 1.3.4 or 1.4.2, which contain fixes that properly sanitize Host header values before processing them in the get_host function. Additionally, application developers should implement supplementary input validation measures, including explicit sanitization of host header values in custom middleware or application code that processes these headers. Security teams should monitor their application logs for unusual Host header patterns and consider implementing web application firewalls that can detect and block malformed Host header values. The fix implemented by Django developers specifically addresses the credential parsing logic within the get_host function, ensuring that username and password components are properly escaped or rejected during URL generation processes. This vulnerability highlights the importance of proper HTTP header validation in web applications and demonstrates how seemingly innocuous parsing functions can create significant security implications when not properly secured against malicious input.