CVE-2001-0892 in thttpd
Summary
by MITRE
Acme Thttpd Secure Webserver before 2.22, with the chroot option enabled, allows remote attackers to view sensitive files under the document root (such as .htpasswd) via a GET request with a trailing /.
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Analysis
by VulDB Data Team • 06/04/2018
The vulnerability described in CVE-2001-0892 represents a critical access control flaw in the Acme Thttpd Secure Webserver version 2.22 and earlier. This issue specifically manifests when the server operates with chroot functionality enabled, creating a scenario where remote attackers can bypass intended security restrictions to access sensitive files within the web document root directory. The vulnerability exploits a fundamental flaw in how the web server processes GET requests that contain trailing slashes, allowing unauthorized information disclosure that could compromise system security.
The technical implementation of this vulnerability stems from improper path handling within the web server's request processing logic. When a GET request is made with a trailing slash character, the server fails to properly validate or sanitize the requested path, enabling attackers to traverse the file system hierarchy and access files that should remain protected. The chroot environment, which is designed to isolate the web server process within a restricted directory tree, becomes ineffective due to this flaw. This particular weakness allows attackers to access configuration files such as .htpasswd, which contain authentication credentials and other sensitive information that should be protected from unauthorized access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential footholds for further exploitation. The ability to access .htpasswd files specifically compromises authentication mechanisms, potentially allowing attackers to gain unauthorized access to protected resources or even escalate privileges within the compromised system. This vulnerability directly violates security principles established by standards such as CWE-22, which addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal attacks. The flaw demonstrates a failure in implementing proper input validation and access control mechanisms that should prevent unauthorized file access regardless of the server's operational mode.
Security professionals should consider this vulnerability in relation to ATT&CK framework techniques such as T1005 (Data from Local System) and T1078 (Valid Accounts), as it enables attackers to collect sensitive data and potentially leverage authentication information for further compromise. The vulnerability affects systems where chroot functionality is enabled as a security measure, making it particularly concerning for environments where this feature is implemented to enhance security boundaries. Organizations should immediately update to version 2.22 or later of the Acme Thttpd Secure Webserver to address this vulnerability, as the flaw represents a fundamental failure in access control that could be exploited for various malicious activities including credential theft and system reconnaissance.
Mitigation strategies should include immediate patching of the web server software, implementation of proper input validation mechanisms, and regular security auditing of web server configurations. System administrators should also consider implementing additional security controls such as web application firewalls and access control lists to prevent exploitation attempts. The vulnerability highlights the importance of proper security testing and validation of security features such as chroot environments, as the intended security benefits can be completely undermined by implementation flaws in core functionality. Regular security assessments and vulnerability scanning should be conducted to identify similar path traversal vulnerabilities in other web server implementations and ensure comprehensive protection against unauthorized access attempts.