CVE-2008-2939 in HTTP Server
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in proxy_ftp.c in the mod_proxy_ftp module in Apache 2.0.63 and earlier, and mod_proxy_ftp.c in the mod_proxy_ftp module in Apache 2.2.9 and earlier 2.2 versions, allows remote attackers to inject arbitrary web script or HTML via a wildcard in the last directory component in the pathname in an FTP URI.
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Analysis
by VulDB Data Team • 01/25/2025
The CVE-2008-2939 vulnerability represents a critical cross-site scripting flaw within the Apache HTTP Server's mod_proxy_ftp module, affecting versions up to 2.0.63 and 2.2.9. This vulnerability resides in the proxy_ftp.c source file and demonstrates a fundamental failure in input validation and output sanitization when processing FTP URIs through the proxy functionality. The flaw specifically manifests when handling wildcard characters within the final directory component of FTP URI pathnames, creating a pathway for malicious actors to inject arbitrary web scripts or HTML content into the server's response handling mechanisms.
The technical exploitation of this vulnerability occurs through the manipulation of FTP URI syntax where attackers can craft malicious URIs containing wildcards in the last directory component of the pathname. When Apache processes these URIs through the mod_proxy_ftp module, the inadequate sanitization of the wildcard characters allows malicious payload injection directly into the HTTP response that gets served to end users. This creates a classic XSS vector where user-supplied input flows directly into the web application's output without proper encoding or validation, enabling attackers to execute arbitrary JavaScript code within the victim's browser context. The vulnerability is particularly dangerous because it leverages the proxy functionality that is often used in enterprise environments for secure access to external resources, making it a prime target for man-in-the-middle attacks and credential theft operations.
The operational impact of CVE-2008-2939 extends beyond simple script injection, as it provides attackers with the capability to perform session hijacking, deface web applications, steal cookies and authentication tokens, and redirect users to malicious domains. This vulnerability directly maps 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. From an ATT&CK framework perspective, this vulnerability enables multiple techniques including T1059.007 for command and scripting interpreter, T1566 for phishing with malicious attachments, and T1071.004 for application layer protocol. The attack surface is particularly concerning in environments where Apache serves as a reverse proxy or forward proxy, as it allows attackers to compromise the entire web application stack through a single vulnerable endpoint.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to Apache versions 2.0.64 and 2.2.10 or later where the fix has been implemented. The recommended approach involves ensuring all proxy configurations are properly validated and that input from external sources is sanitized before processing. Security teams should also implement web application firewalls and content security policies to detect and block malicious payloads, while monitoring for unusual proxy request patterns that might indicate exploitation attempts. Additionally, administrators should review and restrict proxy configurations to minimize the attack surface, particularly disabling unnecessary proxy functionality where possible. The vulnerability underscores the critical importance of input validation in proxy modules and highlights the need for comprehensive security testing of all web server components that handle external URI processing, as the mod_proxy_ftp module represents a common vector for attackers seeking to leverage server-side proxy functionality for malicious purposes.