CVE-2021-20124 in VigorConnect
Summary
by MITRE • 10/13/2021
A local file inclusion vulnerability exists in Draytek VigorConnect 1.6.0-B3 in the file download functionality of the WebServlet endpoint. An unauthenticated attacker could leverage this vulnerability to download arbitrary files from the underlying operating system with root privileges.
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Analysis
by VulDB Data Team • 11/20/2024
The vulnerability identified as CVE-2021-20124 represents a critical local file inclusion flaw within Draytek VigorConnect version 1.6.0-B3, specifically affecting the WebServlet endpoint's file download functionality. This weakness stems from inadequate input validation and sanitization mechanisms that fail to properly restrict file path traversal attempts, allowing malicious actors to manipulate the file download process and access sensitive system resources. The vulnerability resides in the web application's handling of user-supplied parameters during file retrieval operations, creating an attack surface where arbitrary file access becomes possible without authentication requirements.
The technical implementation of this flaw demonstrates a classic path traversal vulnerability where the application directly incorporates user-controllable input into file system operations without proper sanitization. When an attacker submits malicious input to the WebServlet endpoint, the system processes this input without adequate validation, enabling the exploitation of directory traversal sequences such as ../ or ..\ that allow navigation outside the intended file access boundaries. This vulnerability specifically affects the file download functionality, where the application's web interface fails to properly validate file paths, potentially allowing access to system files, configuration data, and other sensitive resources that should remain protected.
The operational impact of this vulnerability is severe and far-reaching, as it grants unauthenticated attackers the ability to download arbitrary files from the underlying operating system with root privileges. This means that an attacker could potentially access critical system files including configuration files, user credentials, system logs, and other sensitive data that could be used for further exploitation or lateral movement within the network. The root privilege access level indicates that the vulnerability allows complete system compromise, potentially enabling attackers to escalate their privileges beyond the initial file access, modify system files, install malware, or establish persistent backdoors. The lack of authentication requirements makes this vulnerability particularly dangerous as it can be exploited by anyone with network access to the affected device, regardless of their authorization status.
This vulnerability maps directly to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The weakness creates a direct pathway for attackers to bypass normal access controls and retrieve files that should be protected from unauthorized access. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.007, which involves the use of command and scripting interpreter for execution, as attackers could potentially use this access to retrieve system tools or scripts that could aid in further exploitation. The vulnerability also relates to T1078.004, which covers valid accounts, as attackers might use this access to obtain information about system accounts or authentication mechanisms that could be leveraged in subsequent attacks.
Mitigation strategies for this vulnerability should include immediate implementation of proper input validation and sanitization measures, ensuring that all user-supplied parameters are thoroughly validated before being processed in file system operations. Network segmentation and access control measures should be implemented to limit exposure of the vulnerable device to untrusted networks. Regular security updates and patches should be applied promptly, with organizations monitoring vendor advisories for security fixes. Additionally, implementing network monitoring and intrusion detection systems can help identify suspicious file access patterns that may indicate exploitation attempts. Organizations should also conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in other networked devices and applications, ensuring comprehensive security coverage across their entire infrastructure.