CVE-2005-0267 in FlatNuke
Summary
by MITRE
index.php in FlatNuke 2.5.1 allows remote attackers to create an administrator account via carriage returns and #10 in the url_avatar field, which is interpreted as a sensitive directive.
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Analysis
by VulDB Data Team • 06/18/2019
The vulnerability identified as CVE-2005-0267 affects FlatNuke version 2.5.1 and represents a critical security flaw in the application's handling of user input within the index.php file. This issue arises from inadequate sanitization of the url_avatar field parameter, which is processed during user account creation or modification processes. The vulnerability specifically exploits how the application interprets certain character sequences including carriage returns and line feed characters, which are commonly represented as #10 in URL encoding contexts. This weakness allows remote attackers to inject malicious content that gets interpreted as sensitive directives within the application's processing logic.
The technical flaw stems from a lack of proper input validation and sanitization mechanisms within the FlatNuke application's user management system. When the url_avatar field receives input containing carriage return characters followed by line feeds, the application's parsing mechanism fails to properly sanitize this input before processing. This creates a scenario where attacker-controlled data can be interpreted as command sequences or configuration directives rather than simple URL references. The vulnerability operates at the application layer and does not require authentication to exploit, making it particularly dangerous as it can be leveraged by any remote user with access to the vulnerable system.
The operational impact of this vulnerability is severe as it allows unauthorized remote attackers to escalate privileges and create administrator accounts within the FlatNuke application. This privilege escalation capability fundamentally compromises the security model of the application, potentially allowing attackers to gain full control over the system. The ability to create administrator accounts means that attackers can modify application settings, access sensitive data, add or remove users, and potentially use the compromised system as a foothold for further attacks within the network. This vulnerability directly violates security principles by enabling unauthorized privilege escalation through improper input handling.
Security mitigations for this vulnerability should focus on implementing comprehensive input validation and sanitization measures within the FlatNuke application. The most effective approach involves filtering out or encoding special characters including carriage returns, line feeds, and other potentially malicious sequences before processing user input. This remediation aligns with CWE-20 standards for input validation and follows the principle of least privilege by ensuring that user-supplied data cannot be interpreted as executable commands or configuration directives. Additionally, implementing proper output encoding and using secure coding practices for parameter handling would prevent similar vulnerabilities from occurring in the future. The fix should also include validating the url_avatar field against a strict whitelist of acceptable URL formats and ensuring that all user input is properly escaped before being processed by the application's internal parsing mechanisms. This vulnerability demonstrates the critical importance of proper input sanitization and represents a classic example of how insufficient validation can lead to privilege escalation attacks.