CVE-2002-1954 in PHP
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the phpinfo function in PHP 4.2.3 allows remote attackers to inject arbitrary web script or HTML via the query string argument, as demonstrated using soinfo.php.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability described in CVE-2002-1954 represents a classic cross-site scripting flaw that existed within PHP's phpinfo function implementation in version 4.2.3. This particular weakness stems from inadequate input validation and output sanitization mechanisms within the phpinfo() function which is commonly used for debugging and system information display purposes. The vulnerability specifically manifests when the function processes query string arguments without proper sanitization, allowing malicious actors to inject arbitrary web scripts or HTML code directly into the response. The attack vector is particularly concerning because it leverages the phpinfo() function which is often accessible and frequently used in development environments, making it an attractive target for exploitation.
The technical flaw resides in how PHP 4.2.3 handled the processing of user-supplied input when the phpinfo() function was invoked with query string parameters. When an attacker crafts a malicious URL containing script tags or HTML content within the query string, the phpinfo() function fails to properly escape or filter this input before rendering it in the web response. This creates a persistent XSS vulnerability where the injected code executes in the context of the victim's browser when they access the affected page. The vulnerability is classified under CWE-79 as "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", which specifically addresses the failure to properly neutralize input data before it is rendered in web pages. This weakness enables attackers to execute malicious scripts in the victim's browser, potentially leading to session hijacking, credential theft, or redirection to malicious sites.
The operational impact of this vulnerability extends beyond simple script injection as it provides attackers with a foothold for more sophisticated attacks within web applications. When exploited, the vulnerability allows remote code execution capabilities through browser-based attacks, potentially enabling attackers to establish persistent access to user sessions or redirect victims to phishing sites. The attack is particularly dangerous in environments where phpinfo() is accessible to end users or when it's used in production environments for debugging purposes. The vulnerability can be exploited through simple URL manipulation techniques, making it accessible to attackers with minimal technical expertise. According to ATT&CK framework, this vulnerability maps to T1566.001 - "Phishing: Spearphishing Attachment" and T1584.004 - "Compromise Infrastructure: Web Shell" as attackers can leverage the XSS to deliver malicious payloads or establish persistent access. The vulnerability also aligns with T1059.007 - "Command and Scripting Interpreter: JavaScript" as it allows execution of JavaScript code within the victim's browser context.
Mitigation strategies for this vulnerability require immediate patching of the affected PHP version to a secure release that properly sanitizes input parameters before processing them through the phpinfo() function. Organizations should implement proper input validation and output encoding mechanisms to prevent similar issues in other functions that may be susceptible to the same type of injection attack. The recommended approach involves ensuring that all user-supplied input is properly escaped before being rendered in web responses, implementing Content Security Policy headers to limit script execution, and restricting access to debug functions like phpinfo() in production environments. Additionally, regular security audits should be conducted to identify and remediate similar vulnerabilities in other web application components. Security teams should also consider implementing web application firewalls to detect and block suspicious query string patterns that could indicate attempted exploitation of XSS vulnerabilities. The vulnerability serves as a reminder of the critical importance of proper input validation and output sanitization in web applications, particularly in functions that generate dynamic content based on user input.