CVE-2021-34820 in HTTP Server
Summary
by MITRE • 07/20/2021
Web Path Directory Traversal in the Novus HTTP Server. The Novus HTTP Server is affected by the Directory Traversal for Arbitrary File Access vulnerability. A remote, unauthenticated attacker using an HTTP GET request may be able to exploit this issue to access sensitive data. The issue was discovered in the NMS (Novus Management System) software through 1.51.2
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/22/2021
The CVE-2021-34820 vulnerability represents a critical directory traversal flaw within the Novus HTTP Server component of the NMS (Novus Management System) software suite. This vulnerability specifically affects versions up to 1.51.2 and exposes the system to remote exploitation by unauthenticated attackers. The flaw resides in how the HTTP server processes file requests, particularly when handling directory traversal sequences in web paths. Attackers can leverage this vulnerability by crafting malicious HTTP GET requests that contain directory traversal sequences such as "../" or similar patterns designed to navigate outside the intended document root directory. The vulnerability falls under the CWE-22 category, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This weakness allows adversaries to access files and directories that are outside the web server's intended document root, potentially leading to unauthorized access to sensitive system information, configuration files, and other restricted resources.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with arbitrary file access capabilities that can be exploited for various malicious purposes. An attacker who successfully exploits this vulnerability can access not only user data but potentially system configuration files, database files, application source code, and other sensitive information that should remain protected. The vulnerability's remote and unauthenticated nature makes it particularly dangerous as it does not require any prior authentication or privileged access to the system. This characteristic aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing for Information) as attackers can systematically explore the file system to discover valuable information without detection. The exploitation of this vulnerability can lead to complete system compromise, data exfiltration, and potentially serve as a foothold for further attacks within the network infrastructure.
Mitigation strategies for CVE-2021-34820 should focus on immediate patching and configuration hardening to prevent exploitation. Organizations should immediately update their Novus Management System installations to versions that contain the patched HTTP server component, as provided by the vendor. Additionally, implementing proper input validation and sanitization measures can help prevent malicious path traversal sequences from being processed by the web server. Network segmentation and firewall rules should be configured to limit access to the affected system, particularly restricting HTTP access from untrusted networks. The implementation of web application firewalls and intrusion detection systems can help detect and block malicious requests containing directory traversal patterns. Security monitoring should include the detection of unusual file access patterns and HTTP requests that attempt to traverse directories beyond the intended web root. Organizations should also conduct thorough security assessments to identify any other potentially vulnerable components within their Novus Management System installations and ensure proper access controls are implemented to minimize the potential impact of such vulnerabilities. The vulnerability's classification as a high-severity issue by security vendors underscores the importance of immediate remediation and ongoing security monitoring to prevent exploitation attempts.