CVE-2008-0456 in HTTP Server
Summary
by MITRE
CRLF injection vulnerability in the mod_negotiation module in the Apache HTTP Server 2.2.6 and earlier in the 2.2.x series, 2.0.61 and earlier in the 2.0.x series, and 1.3.39 and earlier in the 1.3.x series allows remote authenticated users to inject arbitrary HTTP headers and conduct HTTP response splitting attacks by uploading a file with a multi-line name containing HTTP header sequences and a file extension, which leads to injection within a (1) "406 Not Acceptable" or (2) "300 Multiple Choices" HTTP response when the extension is omitted in a request for the file.
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Analysis
by VulDB Data Team • 08/07/2019
The CVE-2008-0456 vulnerability represents a critical CRLF injection flaw within the Apache HTTP Server's mod_negotiation module, affecting multiple versions across the 1.3.x, 2.0.x, and 2.2.x series. This vulnerability operates through a sophisticated attack vector that leverages file naming conventions to inject malicious HTTP headers into server responses. The flaw specifically targets the server's handling of content negotiation when files are requested without their extensions, creating opportunities for attackers to manipulate HTTP responses through carefully crafted file names containing multi-line sequences that include carriage return and line feed characters.
The technical execution of this vulnerability relies on the server's response to requests for files without extensions, where the mod_negotiation module attempts to determine the appropriate content type and generate an appropriate HTTP response. When an authenticated user uploads a file containing multi-line characters in its name, the server processes these names during content negotiation, leading to the injection of arbitrary HTTP headers into the response. This injection occurs specifically during two critical response scenarios: the "406 Not Acceptable" response when the client's Accept header doesn't match the file's content type, and the "300 Multiple Choices" response when multiple content types are available for the requested resource.
The operational impact of this vulnerability extends beyond simple header injection, as it enables HTTP response splitting attacks that can facilitate various malicious activities including session hijacking, cross-site scripting attacks, and cache poisoning. Attackers can exploit this flaw to manipulate HTTP responses in ways that allow them to inject malicious content, redirect users to malicious sites, or manipulate browser behavior through carefully crafted header sequences. The vulnerability's authentication requirement does not mitigate its severity, as authenticated users often have elevated privileges within web applications, making the potential for damage significantly greater.
This vulnerability maps directly to CWE-1107, which specifically addresses "Improper Neutralization of CRLF Sequences in HTTP Headers" and aligns with ATT&CK technique T1190, "Exploit Public-Facing Application," as it represents a server-side vulnerability that can be exploited through web application interfaces. The attack pattern follows the typical progression of HTTP response splitting where initial injection leads to more sophisticated attacks, including the ability to create false responses that can be cached by proxies or browsers. Organizations should implement immediate mitigations including upgrading to patched versions of Apache HTTP Server, implementing proper input validation for file uploads, and configuring appropriate security headers to prevent header injection attacks.
The remediation approach for this vulnerability requires comprehensive patch management across all affected Apache server versions, with particular attention to the mod_negotiation module configuration. Security administrators should disable unnecessary content negotiation features when possible, implement strict file name validation for uploads, and deploy web application firewalls that can detect and block CRLF injection attempts. Additionally, monitoring for unusual file naming patterns and implementing proper logging of content negotiation activities can help detect exploitation attempts. The vulnerability underscores the importance of proper input sanitization in web applications and demonstrates how seemingly benign features like content negotiation can become attack vectors when not properly secured against malicious input manipulation.