CVE-2004-1687 in Forums 2000
Summary
by MITRE
CRLF injection vulnerability in down.asp for Snitz Forums 2000 3.4.04 allows remote attackers to perform HTTP Response Splitting attacks to modify expected HTML content from the server via the location parameter.
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Analysis
by VulDB Data Team • 07/06/2025
The CVE-2004-1687 vulnerability represents a critical security flaw in Snitz Forums 2000 version 3.4.04 that exposes the application to HTTP response splitting attacks through a CRLF injection vector. This vulnerability specifically targets the down.asp script which processes user input through the location parameter, creating an avenue for malicious actors to manipulate HTTP responses and potentially inject arbitrary content into server responses. The flaw stems from inadequate input validation and sanitization mechanisms within the application's handling of user-supplied data, particularly when processing redirect operations.
The technical implementation of this vulnerability involves the manipulation of carriage return line feed sequences within the location parameter to inject additional HTTP headers into the server response. When the application fails to properly sanitize user input, attackers can inject CRLF characters that allow them to insert malicious headers or even entire HTTP responses, effectively splitting the original response and enabling the injection of hostile content. This type of vulnerability falls under CWE-113, which specifically addresses improper neutralization of CRLF characters in HTTP headers, making it a direct descendant of the well-known HTTP response splitting attack pattern.
The operational impact of this vulnerability extends beyond simple content modification, as it provides attackers with the capability to perform session hijacking, cache poisoning, and cross-site scripting attacks by manipulating the HTTP response. An attacker could redirect users to malicious websites, inject malicious scripts into the response, or manipulate browser behavior through header injection, potentially compromising user sessions and exposing sensitive information. The vulnerability particularly affects web applications that rely on user input for redirect operations, making it a significant concern for forum software and other content management systems that handle user-generated redirect parameters.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework under the technique T1566, which covers "Phishing with Spoofed Credentials" and related social engineering attacks that can be facilitated through HTTP response manipulation. The vulnerability's exploitation typically requires minimal privileges and can be automated, making it particularly dangerous in environments where forum software is widely used and accessible to unauthenticated users. Organizations should implement comprehensive input validation, sanitize all user-supplied parameters, and employ proper HTTP response handling mechanisms to prevent CRLF injection attacks. Additionally, the use of web application firewalls and security headers can provide additional layers of protection against such vulnerabilities, while regular security assessments and patch management practices remain essential for maintaining application security posture.