CVE-2007-4906 in NuclearBB
Summary
by MITRE
PHP remote file inclusion vulnerability in tasks/send_queued_emails.php in NuclearBB Alpha 2, when register_globals is enabled, allows remote attackers to execute arbitrary PHP code via a URL in the root_path parameter.
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Analysis
by VulDB Data Team • 10/07/2024
The vulnerability identified as CVE-2007-4906 represents a critical remote file inclusion flaw within the NuclearBB Alpha 2 bulletin board system that exploits the dangerous combination of insecure parameter handling and the deprecated register_globals PHP configuration. This vulnerability specifically affects the tasks/send_queued_emails.php script where user-supplied input is directly incorporated into file inclusion operations without proper validation or sanitization. The flaw occurs when the register_globals directive is enabled in the PHP configuration, which automatically converts HTTP request variables into global variables, creating an attack surface that allows malicious actors to manipulate the application's behavior through crafted input parameters.
The technical implementation of this vulnerability stems from the improper handling of the root_path parameter within the send_queued_emails.php script. When register_globals is enabled, the application fails to properly validate or sanitize user input that gets passed to the include or require statements. Attackers can construct malicious URLs in the root_path parameter that point to remote servers hosting malicious PHP code, enabling arbitrary code execution on the vulnerable system. This type of vulnerability falls under the CWE-88 category for Improper Neutralization of Argument Delimiters in a Command, and more specifically aligns with CWE-94 for Code Injection, where the attacker can inject and execute arbitrary code through the file inclusion mechanism. The vulnerability represents a classic example of how insecure input handling combined with permissive PHP configurations can lead to complete system compromise.
The operational impact of CVE-2007-4906 is severe and encompasses multiple attack vectors that can lead to full system compromise. Successful exploitation allows remote attackers to execute arbitrary PHP code with the privileges of the web server process, potentially enabling them to gain persistent access, escalate privileges, or launch further attacks against the internal network. The vulnerability can be exploited to upload and execute malware, steal sensitive data, modify or delete content, and establish backdoors for continued access. This type of attack aligns with the ATT&CK technique T1190 for Exploit Public-Facing Application, where adversaries target web applications to gain initial access. The impact extends beyond immediate code execution to include potential data breaches, service disruption, and compliance violations, particularly in environments where NuclearBB systems handle sensitive user information or business-critical data.
Mitigation strategies for this vulnerability must address both the immediate security flaw and the underlying configuration issues that enable the attack. The primary recommendation involves disabling the register_globals directive in PHP configuration, as this setting fundamentally undermines application security by automatically creating global variables from user input. Additionally, all input parameters, particularly those used in file inclusion operations, must be properly validated and sanitized through strict input filtering and whitelisting mechanisms. The application code should be updated to use absolute paths instead of user-supplied parameters for file operations, and proper error handling should be implemented to prevent information disclosure. Security measures should include regular vulnerability assessments, web application firewalls, and monitoring for suspicious file inclusion patterns. Organizations should also consider implementing principle of least privilege for web server accounts and regularly updating their software to address known vulnerabilities, as this particular flaw existed in a deprecated version of NuclearBB that would not receive security updates. The vulnerability demonstrates the critical importance of secure coding practices and proper configuration management in preventing remote code execution attacks.