CVE-2006-0760 in LightTPD
Summary
by MITRE
LightTPD 1.4.8 and earlier, when the web root is on a case-insensitive filesystem, allows remote attackers to bypass URL checks and obtain sensitive information via file extensions with unexpected capitalization, as demonstrated by a request for index.PHP when the configuration invokes the PHP interpreter only for ".php" names.
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Analysis
by VulDB Data Team • 03/23/2017
The vulnerability described in CVE-2006-0760 represents a critical security flaw in LightTPD web servers version 1.4.8 and earlier, specifically when operating on filesystems that do not distinguish between uppercase and lowercase file extensions. This issue stems from the server's inadequate handling of case-sensitive filename comparisons during URL processing, creating a pathway for unauthorized access to sensitive resources. The flaw exploits the fundamental mismatch between how the web server processes file extensions and how the underlying filesystem interprets them, particularly when the filesystem operates in a case-insensitive mode. When a request is made for a file with an unconventional capitalization pattern such as index.PHP instead of the expected index.php, the server fails to properly validate the extension against its configured MIME type mappings, allowing malicious actors to bypass intended security restrictions.
The technical implementation of this vulnerability involves the web server's configuration parsing and file extension validation mechanisms. In LightTPD, administrators typically configure specific file extensions to trigger particular interpreters or handlers, such as mapping .php files to the PHP interpreter for execution. However, when operating on case-insensitive filesystems, the server's internal logic does not properly normalize or validate the case of file extensions before performing these mappings. This creates a scenario where a request for index.PHP might be processed as if it were index.php, potentially bypassing security controls that depend on exact extension matching. The vulnerability is particularly dangerous because it can be exploited to access files that should be protected or restricted, such as configuration files, backup files, or other sensitive resources that are normally not accessible through standard web requests.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a fundamental flaw in access control mechanisms that could enable more sophisticated attacks. Attackers can leverage this weakness to access files that are typically protected by extension-based security controls, potentially leading to complete system compromise. The vulnerability is especially concerning in environments where LightTPD serves dynamic content or where sensitive files are stored in web-accessible directories. According to CWE-200, this represents a weakness in information disclosure, while the attack pattern aligns with techniques described in ATT&CK framework under T1083 (File and Directory Discovery) and T1566 (Phishing). The flaw essentially allows attackers to perform unauthorized file access by manipulating the case of file extensions, potentially exposing sensitive data or enabling further exploitation through access to configuration files or backup copies.
Mitigation strategies for CVE-2006-0760 require immediate attention from system administrators and security teams. The most effective solution involves upgrading to LightTPD version 1.4.9 or later, which contains the necessary fixes to properly handle case-sensitive file extension validation. Organizations should also implement strict file extension validation in their server configurations, ensuring that all extension mappings are explicitly defined and that case-sensitive matching is enforced regardless of filesystem characteristics. Additionally, system administrators should conduct comprehensive audits of their web server configurations to identify any potential misconfigurations that might create similar vulnerabilities. The implementation of proper access controls, including mandatory file extension validation and case normalization, should be enforced at the server level to prevent such bypasses. Security teams should also consider implementing monitoring solutions that can detect unusual file access patterns or requests that attempt to exploit case-insensitive filesystem behaviors, providing early warning of potential exploitation attempts.