CVE-2001-0766 in HTTP Server
Summary
by MITRE
Apache on MacOS X Client 10.0.3 with the HFS+ file system allows remote attackers to bypass access restrictions via a URL that contains some characters whose case is not matched by Apache s filters.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability described in CVE-2001-0766 represents a significant access control flaw in the Apache web server implementation on MacOS X Client 10.0.3 systems utilizing the HFS+ file system. This issue stems from the improper handling of case sensitivity in URL parsing and file system access controls, creating a pathway for remote attackers to circumvent intended security restrictions. The vulnerability specifically exploits the difference in how Apache processes URL case sensitivity compared to the HFS+ file system's case-insensitive nature, allowing malicious actors to access files and directories that should otherwise be restricted.
The technical root cause of this vulnerability lies in Apache's URL filtering mechanisms which fail to properly normalize case variations when processing file paths. In HFS+ file systems, filenames are case-insensitive, meaning that files named "document.html" and "DOCUMENT.HTML" are treated as identical. However, Apache's access control filters on MacOS X Client 10.0.3 do not account for this case insensitivity, creating a mismatch where URL paths with different casing can successfully access files that are protected by access restrictions. This flaw operates at the intersection of web server configuration and file system behavior, where the server's interpretation of access control rules does not align with the underlying file system's case handling mechanisms.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can enable attackers to bypass directory listing restrictions, access protected administrative files, and potentially escalate privileges within the web server environment. Attackers can craft URLs with specific case variations that appear to target restricted resources but actually resolve to legitimate files due to the case-insensitive nature of HFS+. This vulnerability particularly affects environments where Apache serves content from HFS+ volumes and where access controls are implemented through directory permissions or .htaccess files. The remote nature of the attack means that exploitation does not require local system access, making it a significant concern for web applications hosted on affected MacOS X systems.
Security practitioners should recognize this vulnerability as a variant of improper input validation and access control bypass issues, aligning with CWE-284 which addresses improper access control in software systems. The attack pattern corresponds to techniques described in the ATT&CK framework under privilege escalation and defense evasion tactics, where adversaries exploit implementation flaws in access control mechanisms. Organizations should implement immediate mitigations including upgrading to patched versions of Apache and MacOS X, implementing additional access control layers, and conducting thorough audits of file system permissions and web server configurations. The vulnerability also highlights the importance of understanding platform-specific file system behaviors when implementing security controls, as the mismatch between Apache's case handling and HFS+'s case insensitivity created the exploitable condition.