CVE-2002-2418 in acFreeProxy
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in acFreeProxy (aka acFP) 1.33 beta 7 allows remote attackers to inject arbitrary web script or HTML via the URL, which is inserted into an error page.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/26/2025
The CVE-2002-2418 vulnerability represents a classic cross-site scripting flaw in the acFreeProxy 1.33 beta 7 web proxy application that demonstrates how improperly sanitized user input can lead to significant security risks. This vulnerability specifically affects the error handling mechanism of the proxy software where user-supplied URLs are directly incorporated into error pages without proper sanitization or encoding. The flaw exists at the application layer where the proxy fails to validate or escape input parameters before rendering them in the context of web page content, creating an environment where malicious actors can execute arbitrary scripts in the victim's browser.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious URL that contains script code within its parameters and submits it to the vulnerable proxy server. When the proxy encounters an error while processing this URL, it renders the malicious input directly into the error page without proper HTML encoding or script sanitization. This creates a persistent XSS vector where any user who views the error page becomes a victim of the attack. The vulnerability maps directly to CWE-79 which defines Cross-Site Scripting as a weakness where untrusted data is sent to a web browser without proper validation or encoding. The attack pattern follows the standard XSS methodology where malicious code embedded in URL parameters executes within the context of the victim's browser session, potentially leading to session hijacking, credential theft, or redirection to malicious sites.
The operational impact of this vulnerability extends beyond simple script execution as it compromises the fundamental security assumptions of web proxy systems. In a corporate or organizational environment where acFreeProxy is deployed, this vulnerability could allow attackers to bypass security controls by injecting malicious scripts that can steal cookies, session tokens, or other sensitive information from users accessing the proxy. The vulnerability affects not just the immediate proxy functionality but also undermines trust in the entire proxy infrastructure, as users may be unaware that their browser is executing malicious code without their knowledge. The attack vector is particularly dangerous because it requires no special privileges or authentication, making it an attractive target for automated attacks. This vulnerability aligns with ATT&CK technique T1566 which covers social engineering attacks through malicious web content, and specifically T1212 which addresses exploitation of web application vulnerabilities.
Mitigation strategies for CVE-2002-2418 should focus on implementing proper input validation and output encoding mechanisms within the proxy application. The most effective immediate fix involves sanitizing all user-supplied input before it is rendered in any web context, particularly error pages. This includes implementing HTML entity encoding for all dynamic content that originates from user input, which prevents script execution by converting special characters into their encoded equivalents. Additionally, the proxy should implement proper content security policies that restrict script execution within the error page context. Organizations should also consider implementing web application firewalls that can detect and block XSS attempts, though the most robust solution involves patching the underlying application vulnerability. The fix should align with industry best practices for secure coding and specifically address the OWASP Top 10 vulnerability categories, particularly the XSS prevention guidelines that emphasize the importance of proper input sanitization and output encoding. Regular security audits and code reviews should be conducted to ensure that similar vulnerabilities are not present in other components of the proxy system or related applications.