CVE-2003-0395 in Ultimate PHP Board UPB
Summary
by MITRE
Ultimate PHP Board (UPB) 1.9 allows remote attackers to execute arbitrary PHP code with UPB administrator privileges via an HTTP request containing the code in the User-Agent header, which is executed when the administrator executes admin_iplog.php.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2003-0395 represents a critical remote code execution flaw within the Ultimate PHP Board 1.9 web application. This security weakness stems from improper input validation and sanitization mechanisms that fail to adequately filter user-provided data before processing. The vulnerability specifically manifests when administrators access the admin_iplog.php management interface, creating a dangerous attack vector that can be exploited by remote adversaries without requiring authentication credentials. The attack leverages the User-Agent HTTP header as an injection point, which is a common technique for bypassing traditional security controls and exploiting applications that fail to properly validate all request parameters.
The technical implementation of this vulnerability demonstrates a classic case of insecure input handling where the application directly incorporates user-supplied data into executable code paths. When an administrator visits the admin_iplog.php page, the application processes the User-Agent header without sufficient sanitization, allowing malicious code embedded within this header to be executed with the elevated privileges of the administrator account. This privilege escalation aspect significantly amplifies the impact of the vulnerability, as attackers can leverage this to gain full administrative control over the affected web application. The flaw falls under the category of code injection vulnerabilities, specifically aligning with CWE-94 which describes "Improper Control of Generation of Code ('Code Injection')" and represents a subset of the broader CWE-77 category for command injection attacks.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete administrative access to the Ultimate PHP Board installation. This access enables unauthorized modification of forum content, user account manipulation, data exfiltration, and potential lateral movement within the compromised network. The vulnerability's remote exploitability means that attackers can target the system from anywhere on the internet without requiring physical access or prior authentication. From an attacker's perspective, this represents a low-effort, high-reward attack vector that can be automated and scaled across multiple targets, making it particularly dangerous in environments where such legacy applications remain operational. The vulnerability also demonstrates poor security architecture practices that violate fundamental principles of defense in depth and input validation.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected Ultimate PHP Board version to the latest available security updates from the vendor. Organizations should implement comprehensive input validation mechanisms that sanitize all HTTP headers before processing, particularly those that may be used in code execution contexts. Network-level protections such as web application firewalls can provide additional defense layers by monitoring and filtering suspicious User-Agent patterns. The implementation of principle of least privilege should be enforced, ensuring that administrative interfaces are only accessible from trusted network segments and that access controls are properly configured. Security monitoring should include detection of anomalous User-Agent strings and unusual administrative access patterns. This vulnerability also highlights the importance of regular security assessments and vulnerability scanning to identify similar flaws in legacy applications, as the ATT&CK framework would categorize this as a privilege escalation technique through application exploitation. Organizations should also consider implementing proper code review processes and automated security testing to prevent similar injection vulnerabilities in future development cycles.