CVE-2021-21879 in PremierWave
Summary
by MITRE • 12/22/2021
A directory traversal vulnerability exists in the Web Manager File Upload functionality of Lantronix PremierWave 2050 8.9.0.0R4. A specially-crafted HTTP request can lead to arbitrary file overwrite. An attacker can make an authenticated HTTP request to trigger this vulnerability.
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Analysis
by VulDB Data Team • 12/26/2021
The vulnerability identified as CVE-2021-21879 represents a critical directory traversal flaw within the Web Manager File Upload functionality of Lantronix PremierWave 2050 version 8.9.0.0R4. This issue falls under the CWE-22 category of Improper Limitation of a Pathname to a Restricted Directory, commonly known as Path Traversal, which is a fundamental security weakness that allows attackers to access files and directories outside the intended scope. The vulnerability specifically affects the web-based management interface of the network device, creating a pathway for unauthorized file manipulation through the file upload mechanism that is designed to be restricted to legitimate administrative operations.
The technical exploitation of this vulnerability requires an authenticated attacker who can submit a specially crafted HTTP request to the affected web manager interface. This authentication requirement means that the vulnerability cannot be exploited anonymously, but it does represent a significant risk when considering that legitimate users with appropriate credentials could potentially leverage this flaw to overwrite arbitrary files on the system. The attack vector specifically targets the file upload functionality, where the application fails to properly validate or sanitize user-supplied file paths, allowing attackers to manipulate the destination path of uploaded files through directory traversal sequences such as ../ or ..\ that can navigate outside the intended upload directory. The vulnerability enables attackers to overwrite existing files on the device's file system, potentially compromising system integrity and allowing for persistent access or further exploitation.
The operational impact of this vulnerability extends beyond simple file overwrites, as it creates opportunities for attackers to modify critical system files, configuration data, or even replace executable components with malicious versions. This capability can lead to complete system compromise, denial of service conditions, or the establishment of persistent backdoors within the network infrastructure. The PremierWave 2050 device, being a network management appliance, serves as a critical component in industrial and enterprise environments, making this vulnerability particularly dangerous as it could affect network operations and potentially provide attackers with a foothold for lateral movement within the network. The authenticated nature of the attack means that this vulnerability could be exploited by insiders with legitimate access or by attackers who have obtained valid credentials through other means, such as credential theft or social engineering attacks.
Mitigation strategies for CVE-2021-21879 should focus on immediate patching of the affected firmware version to address the directory traversal vulnerability in the file upload functionality. Organizations should also implement network segmentation to limit access to the web manager interface, ensuring that only authorized administrative systems can reach the device. Additional defensive measures include implementing strict access controls, monitoring for unusual file upload patterns, and conducting regular security assessments of network management interfaces. The vulnerability highlights the importance of input validation and proper path handling in web applications, particularly in administrative interfaces where file operations are performed. Security teams should also consider implementing web application firewalls to detect and block suspicious HTTP requests that may attempt to exploit similar directory traversal vulnerabilities. According to ATT&CK framework, this vulnerability maps to T1078 Valid Accounts and T1566 Phishing with the potential for privilege escalation and lateral movement, making it a significant concern for enterprise security postures. The incident also underscores the necessity of secure coding practices and thorough security testing of network management interfaces to prevent unauthorized file system access through authenticated pathways.