CVE-2008-0005 in HTTP Server
Summary
by MITRE
mod_proxy_ftp in Apache 2.2.x before 2.2.7-dev, 2.0.x before 2.0.62-dev, and 1.3.x before 1.3.40-dev does not define a charset, which allows remote attackers to conduct cross-site scripting (XSS) attacks using UTF-7 encoding.
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Analysis
by VulDB Data Team • 08/03/2019
The vulnerability described in CVE-2008-0005 affects Apache's mod_proxy_ftp module, which serves as a reverse proxy for ftp resources. This issue specifically impacts Apache versions prior to 2.2.7-dev, 2.0.62-dev, and 1.3.40-dev, where the module fails to properly define character encoding when processing ftp responses. The flaw stems from the module's inability to correctly handle UTF-7 encoding sequences, creating a potential cross-site scripting vector that remote attackers can exploit. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically manifesting as an input validation weakness in the proxy module's character set handling. The issue represents a classic case of improper input sanitization where the module accepts ftp responses without proper encoding specification, allowing malicious content to be interpreted as executable script code in web browsers.
The technical exploitation of this vulnerability occurs when mod_proxy_ftp processes ftp responses that contain UTF-7 encoded content. UTF-7 encoding is a legacy encoding method that can represent unicode characters using 7-bit ascii, but it has been deprecated due to security concerns. When an attacker crafts an ftp response containing UTF-7 encoded malicious content, and this content passes through the vulnerable mod_proxy_ftp module without proper charset definition, browsers may interpret the UTF-7 sequences as regular ascii characters, inadvertently executing the embedded malicious script. This process aligns with ATT&CK technique T1211 which involves exploitation of proxy modules and web application vulnerabilities through improper content handling. The vulnerability demonstrates how proxy modules can become attack vectors when they fail to properly sanitize or define character encodings for content they process and forward to end users.
The operational impact of this vulnerability extends beyond simple XSS attacks, as it can enable attackers to perform session hijacking, steal sensitive information, or redirect users to malicious websites. The vulnerability is particularly concerning in environments where Apache serves as a reverse proxy for ftp resources, as it affects all versions of Apache 1.3, 2.0, and 2.2 series that lack the security patches. Organizations relying on mod_proxy_ftp for ftp access through web interfaces face significant risk, as this vulnerability can be exploited without requiring authentication or special privileges. The attack can be executed through simple ftp response manipulation, making it accessible to attackers with minimal technical expertise. This issue represents a fundamental security flaw in the proxy module's content processing pipeline, where the lack of explicit charset definition creates a dangerous gap in the security architecture that can be exploited by attackers to compromise user sessions and data integrity. The vulnerability's impact is amplified by the fact that it affects multiple major Apache versions simultaneously, suggesting a systemic issue in the module's design and implementation approach.
Mitigation strategies for CVE-2008-0005 involve immediate patching of affected Apache installations to versions that properly define character sets in mod_proxy_ftp responses. Organizations should implement comprehensive monitoring of their proxy configurations to ensure proper charset handling across all modules. Network segmentation and access controls should be enforced to limit exposure of vulnerable proxy configurations. Additionally, implementing web application firewalls and content security policies can provide additional protection layers against exploitation attempts. The fix typically involves updating to Apache versions 2.2.7-dev, 2.0.62-dev, or 1.3.40-dev where the charset handling has been corrected. Security teams should also conduct regular vulnerability assessments focusing on proxy module configurations and ensure that all character encoding specifications are properly defined in web application components. This vulnerability serves as a reminder of the importance of proper encoding handling in proxy modules and the critical need for maintaining up-to-date security patches across all web server components.