CVE-2011-3186 in Ruby on Rails
Summary
by MITRE
CRLF injection vulnerability in actionpack/lib/action_controller/response.rb in Ruby on Rails 2.3.x before 2.3.13 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via the Content-Type header.
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Analysis
by VulDB Data Team • 11/18/2021
The CVE-2011-3186 vulnerability represents a critical CRLF injection flaw within the Ruby on Rails web application framework that specifically affects versions 2.3.x prior to 2.3.13. This vulnerability resides in the actionpack component, more precisely within the action_controller/response.rb file, where the framework fails to properly sanitize user input when processing HTTP headers. The flaw enables malicious actors to inject carriage return line feed sequences into HTTP responses, fundamentally compromising the integrity of the web application's header processing mechanisms. Such vulnerabilities fall under the CWE-113 category, which specifically addresses improper neutralization of CRLF characters within HTTP headers, making them susceptible to various attack vectors including HTTP response splitting.
The technical exploitation of this vulnerability occurs when the Ruby on Rails application processes a Content-Type header that contains malicious CRLF sequences. Attackers can append newline characters followed by additional HTTP headers to manipulate the response structure, potentially allowing them to inject arbitrary headers into the HTTP response sent to clients. This manipulation enables attackers to perform HTTP response splitting attacks, where they can inject multiple HTTP responses into a single response, effectively bypassing security controls and potentially enabling session hijacking, cross-site scripting attacks, or cache poisoning techniques. The vulnerability specifically targets the response handling mechanism, making it particularly dangerous for applications that rely heavily on dynamic header generation or user-supplied content in their HTTP responses.
The operational impact of CVE-2011-3186 extends beyond simple header injection, as it provides attackers with a foothold for more sophisticated attacks within web application environments. When successfully exploited, this vulnerability can lead to complete session compromise, as attackers can manipulate cookies and authentication headers to hijack user sessions. The vulnerability also enables cache poisoning attacks where malicious content can be injected into web caches, affecting multiple users simultaneously. Additionally, the ability to inject arbitrary HTTP headers can facilitate cross-site scripting attacks by manipulating the Content-Security-Policy header or other security-related headers. From an ATT&CK framework perspective, this vulnerability maps to T1190 - Exploit Public-Facing Application and T1566 - Phishing, as it provides initial access vectors that can lead to further compromise of web application environments. Organizations running affected versions of Ruby on Rails face significant risk of unauthorized access, data theft, and potential system compromise.
Mitigation strategies for CVE-2011-3186 primarily involve immediate patching of Ruby on Rails applications to version 2.3.13 or later, which includes proper sanitization of HTTP headers to prevent CRLF injection. Organizations should also implement input validation and sanitization at multiple layers of their application architecture, ensuring that all user-supplied data is properly escaped before being processed in HTTP headers. Network-level protections such as web application firewalls can provide additional defense in depth, though they should not be relied upon as the sole mitigation. Security monitoring should include detection of unusual header patterns and malformed HTTP responses that might indicate exploitation attempts. The vulnerability highlights the importance of secure coding practices and input validation, particularly in frameworks that handle HTTP response generation, as it demonstrates how seemingly minor flaws in header processing can lead to significant security implications. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other components of the web application stack, as this vulnerability represents a pattern that can occur in various forms across different frameworks and technologies.