CVE-2021-20125 in VigorConnect
Summary
by MITRE • 10/13/2021
An arbitrary file upload and directory traversal vulnerability exists in the file upload functionality of DownloadFileServlet in Draytek VigorConnect 1.6.0-B3. An unauthenticated attacker could leverage this vulnerability to upload files to any location on the target operating system with root privileges.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 10/20/2021
The vulnerability identified as CVE-2021-20125 represents a critical security flaw in Draytek VigorConnect 1.6.0-B3 that combines arbitrary file upload capabilities with directory traversal exploitation. This vulnerability resides within the DownloadFileServlet component of the network management software, which is designed to handle file transfer operations for network devices. The flaw allows attackers to bypass authentication mechanisms and gain unrestricted access to the underlying operating system with the highest possible privileges, effectively providing complete system compromise. The vulnerability's severity is amplified by the fact that it requires no authentication, making it particularly dangerous for network administrators who may unknowingly expose their systems to remote exploitation.
Technical exploitation of this vulnerability occurs through the manipulation of file upload parameters within the DownloadFileServlet interface. The flawed implementation fails to properly validate file paths and names, allowing attackers to craft malicious requests that traverse directory structures and place arbitrary files in critical system locations. This directory traversal capability, combined with the ability to upload executable files, creates a perfect storm for privilege escalation attacks. The vulnerability specifically affects the file upload functionality where user-supplied input is directly incorporated into file system operations without adequate sanitization or access control checks. According to CWE classification, this vulnerability maps to CWE-22 Directory Traversal and CWE-434 Unrestricted Upload of File, both of which are well-documented in the Common Weakness Enumeration database. The attack vector follows the pattern described in MITRE ATT&CK framework under T1059 Command and Scripting Interpreter and T1566 Phishing, as attackers can leverage this vulnerability to establish persistent access and potentially escalate privileges to root level.
The operational impact of CVE-2021-20125 extends far beyond simple data compromise, as successful exploitation provides attackers with complete system control and root privileges. Network administrators managing Draytek VigorConnect systems are at risk of having their entire network infrastructure compromised, as the vulnerability allows for the deployment of backdoors, malware, and other malicious payloads that can persist across system reboots. The implications are particularly severe for enterprise environments where these devices often serve as critical network management points, potentially enabling attackers to gain visibility into network traffic, manipulate device configurations, or establish lateral movement capabilities. Organizations using this software may face regulatory compliance issues, as the vulnerability could lead to unauthorized access to sensitive network data and disruption of critical business operations. The lack of authentication requirements means that this vulnerability can be exploited remotely without any prior access credentials, making it especially dangerous for publicly accessible network management interfaces.
Mitigation strategies for CVE-2021-20125 should prioritize immediate software updates from Draytek to address the root cause of the vulnerability. Organizations should implement network segmentation to limit access to VigorConnect management interfaces and deploy network monitoring solutions to detect anomalous file upload activities. Security configurations should include input validation mechanisms, proper access controls, and regular security assessments to identify similar vulnerabilities in other network management tools. The vulnerability highlights the importance of secure coding practices and proper validation of user-supplied data in web applications, as emphasized by OWASP Top Ten and NIST cybersecurity guidelines. Additionally, organizations should conduct regular vulnerability assessments of their network infrastructure and maintain up-to-date security patches to prevent exploitation of similar weaknesses in other software components. Given the severity of this vulnerability, immediate action is required to prevent potential exploitation and maintain network security posture.