CVE-2002-1445 in CERN httpd
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in CERN Proxy Server allows remote attackers to execute script as other users via a link to a non-existent page whose name contains the script, which is inserted into the resulting error page.
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Analysis
by VulDB Data Team • 03/31/2025
The CVE-2002-1445 vulnerability represents a classic cross-site scripting flaw in the CERN Proxy Server that demonstrates how improperly handled error messages can create security risks for web applications. This vulnerability specifically targets the server's handling of requests for non-existent pages, where the requested resource name becomes embedded in error responses without proper sanitization or encoding. The flaw exists in the server's error page generation mechanism, which fails to adequately escape or filter user-supplied input before displaying it within the HTML context of the error message. This creates an environment where malicious actors can craft URLs containing malicious script code that gets executed when users click on links to nonexistent resources, effectively enabling the proxy server to serve as an unwitting vector for XSS attacks.
The technical implementation of this vulnerability stems from the proxy server's failure to properly sanitize user input during error page construction, which directly maps to CWE-79 - Improper Neutralization of Input During Web Page Generation. When a user attempts to access a non-existent page with malicious script content in the URL, the proxy server processes this request and generates an error page that includes the raw user input in the response body. The server's HTML rendering engine does not escape special characters or apply proper output encoding, allowing the injected script to execute within the browser context of other users who view the error page. This vulnerability operates at the application layer and can be classified under the ATT&CK technique T1059.001 - Command and Scripting Interpreter: JavaScript, as it leverages JavaScript execution capabilities to compromise user sessions and potentially escalate privileges.
The operational impact of CVE-2002-1445 extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal cookies, redirect users to malicious sites, or inject persistent malware into victim browsers. Since the proxy server acts as an intermediary between users and web resources, the vulnerability can affect multiple users simultaneously when they encounter the malicious error page. The attack requires minimal sophistication and can be executed through simple URL manipulation, making it particularly dangerous in environments where users frequently click on links or where the proxy server serves as a gateway to internal corporate resources. The vulnerability affects the integrity of web content and user trust, as legitimate users may unknowingly encounter malicious scripts during normal browsing activities when the proxy server generates error messages.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and output encoding mechanisms within the proxy server's error handling routines. Organizations should ensure that all user-supplied input is sanitized before being displayed in error contexts, applying HTML entity encoding to prevent script execution. The proxy server configuration should include automatic escaping of special characters in error messages, particularly when displaying requested URLs or resource names. Security measures should also incorporate regular security assessments of web proxy configurations and implement monitoring for suspicious error page generation patterns. Organizations can also deploy web application firewalls or security proxies that can detect and block malicious script injection attempts, while maintaining proper logging and alerting mechanisms to identify potential exploitation attempts. The fix should align with security best practices outlined in OWASP Top Ten and NIST guidelines for preventing cross-site scripting vulnerabilities in web applications.