CVE-2005-1894 in FlatNuke
Summary
by MITRE
Direct code injection vulnerability in FlatNuke 2.5.3 allows remote attackers to execute arbitrary PHP code by placing the code into the Referer header of an HTTP request, which causes the code to be injected into referer.php, which can then be accessed by the attacker.
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Analysis
by VulDB Data Team • 07/07/2025
The vulnerability identified as CVE-2005-1894 represents a critical direct code injection flaw within FlatNuke 2.5.3 content management system that exposes the application to remote code execution attacks. This vulnerability operates through a sophisticated attack vector that leverages HTTP header manipulation to inject malicious PHP code directly into the application's processing pipeline. The flaw specifically targets the referer.php component which serves as a critical interface for handling HTTP referer information within the FlatNuke framework, making it an attractive target for attackers seeking to compromise the system. The vulnerability manifests when the application fails to properly sanitize or validate the Referer header input, allowing attackers to inject arbitrary PHP code that gets executed within the context of the web server.
The technical exploitation of this vulnerability follows a well-defined pattern that aligns with common web application attack methodologies and maps directly to CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')." Attackers can craft malicious HTTP requests containing PHP code within the Referer header field, which the vulnerable FlatNuke application processes without adequate input validation or sanitization. When the referer.php script executes, it incorporates the malicious code from the header into its processing logic, effectively creating a backdoor that allows attackers to execute arbitrary commands on the compromised system. This type of injection vulnerability demonstrates a fundamental failure in input validation and output encoding practices that violates core security principles outlined in the OWASP Top Ten and other industry standards for secure coding practices.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and potential data breaches. Attackers who successfully exploit this vulnerability can gain unauthorized access to the web server hosting the FlatNuke application, potentially leading to full system control, data exfiltration, and the ability to use the compromised server as a launching point for further attacks against the internal network. The vulnerability's remote nature means that attackers do not require physical access or prior authentication to exploit the flaw, making it particularly dangerous in production environments where the application may be exposed to the internet. This type of vulnerability also aligns with ATT&CK technique T1059.007, which covers "Command and Scripting Interpreter: Python," as the injected PHP code can execute system commands and manipulate the underlying operating system.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements within the FlatNuke application architecture. The most direct and effective solution involves implementing comprehensive input validation and sanitization for all HTTP headers, particularly the Referer header, ensuring that any potentially malicious content is properly escaped or filtered before processing. Organizations should also consider implementing web application firewalls that can detect and block suspicious header content patterns, as well as deploying proper output encoding mechanisms that prevent code injection attacks from succeeding. The vulnerability highlights the critical importance of input validation and the principle of least privilege in web application security, where all user-supplied data should be treated as potentially malicious and properly validated before being processed by the application. Regular security audits and code reviews should be implemented to identify similar vulnerabilities in other components of the system, and the application should be updated to newer versions that have addressed this specific flaw in their security implementations.