CVE-2021-20145 in Tower Router
Summary
by MITRE • 12/09/2021
Gryphon Tower routers contain an unprotected openvpn configuration file which can grant attackers access to the Gryphon homebound VPN network which exposes the LAN interfaces of other users' devices connected to the same service. An attacker could leverage this to make configuration changes to, or otherwise attack victims' devices as though they were on an adjacent network.
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Analysis
by VulDB Data Team • 12/15/2021
The vulnerability identified as CVE-2021-20145 affects Gryphon Tower routers, representing a critical security flaw that compromises the integrity of home VPN networks. This vulnerability stems from the improper configuration of openvpn settings within the router firmware, creating an unprotected access point that exposes the underlying network infrastructure to unauthorized parties. The flaw essentially allows attackers to gain unauthorized access to the VPN network, which serves as a gateway to the local area networks of other connected users, fundamentally undermining the security model that VPNs are designed to provide.
The technical implementation of this vulnerability involves the exposure of sensitive configuration files that contain authentication credentials and network parameters necessary for establishing VPN connections. These unprotected files typically contain information such as usernames, passwords, and network access details that should remain confidential within a properly secured environment. The flaw demonstrates a clear failure in proper access control mechanisms, where sensitive network configuration data is accessible without authentication, violating fundamental security principles of network segmentation and access control. This vulnerability directly maps to CWE-200, which addresses improper exposure of sensitive information, and represents a classic example of insufficient access control measures.
The operational impact of this vulnerability extends far beyond simple unauthorized access, creating a significant risk for all users within the same VPN service network. Attackers who exploit this vulnerability can effectively position themselves within the network as if they were legitimate users on the same local network, enabling them to perform man-in-the-middle attacks, intercept communications, and potentially escalate privileges to gain control over other connected devices. This creates a domino effect where a single compromised router can provide attackers with access to multiple victim devices, potentially including IoT devices, computers, and networked appliances that may have additional vulnerabilities. The threat landscape is particularly concerning given that these devices often lack the security measures found on traditional computing systems, making them prime targets for exploitation.
From an attack perspective, this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to initial access and privilege escalation. Attackers can leverage this vulnerability to establish a foothold within the network, then use the compromised router as a pivot point to explore and attack other systems within the same network segment. The exposure of the VPN configuration also enables attackers to conduct reconnaissance activities, mapping network topology and identifying additional targets within the compromised network. Organizations and individuals should implement immediate mitigations including firmware updates from the vendor, network segmentation to isolate VPN users, and the implementation of additional access controls to prevent unauthorized configuration changes. The vulnerability highlights the importance of proper network security configuration management and the critical need for regular security assessments to identify and remediate similar exposure points within network infrastructure.