CVE-2020-3330 in RV110W
Summary
by MITRE
A vulnerability in the Telnet service of Cisco Small Business RV110W Wireless-N VPN Firewall Routers could allow an unauthenticated, remote attacker to take full control of the device with a high-privileged account. The vulnerability exists because a system account has a default and static password. An attacker could exploit this vulnerability by using this default account to connect to the affected system. A successful exploit could allow the attacker to gain full control of an affected device.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/03/2020
The CVE-2020-3330 vulnerability represents a critical security flaw in Cisco Small Business RV110W Wireless-N VPN Firewall routers that demonstrates the persistent dangers of hardcoded credentials in network infrastructure devices. This vulnerability specifically targets the Telnet service implementation within the affected router firmware, where a system account possesses a default and static password that remains unchanged across all deployments. The flaw exists at the authentication layer and represents a fundamental failure in secure configuration practices, where manufacturers fail to implement proper credential management or account disablement for default administrative accounts. This vulnerability directly maps to CWE-798, which identifies the use of hard-coded credentials as a significant security risk, and aligns with ATT&CK technique T1078.004 which covers legitimate credentials used for persistence and privilege escalation.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it provides attackers with full administrative control over the affected network infrastructure. An unauthenticated remote attacker can exploit this weakness by simply connecting to the Telnet service using the default account credentials, bypassing all normal authentication mechanisms and gaining elevated privileges without requiring any specialized tools or techniques. This level of access enables attackers to modify network configurations, redirect traffic, install malicious software, or establish backdoors for persistent access. The vulnerability affects the router's core network security functions, potentially allowing attackers to compromise the entire local network segment that the device protects, making it particularly dangerous for small business environments where these devices often serve as the primary network gateway.
The exploitation of this vulnerability demonstrates how default credentials continue to represent one of the most prevalent attack vectors in network security, with attackers routinely scanning for and exploiting these known weaknesses. Network administrators who fail to properly secure their devices by changing default passwords or disabling unused services create an opening that requires minimal effort to exploit. This vulnerability highlights the importance of implementing the principle of least privilege and proper secure configuration management, where default accounts should be disabled or have their credentials changed immediately upon device deployment. The security implications extend to compliance requirements such as those outlined in NIST SP 800-171 and ISO 27001, which mandate proper credential management and access control measures to prevent unauthorized access to critical network infrastructure components.
Mitigation strategies for CVE-2020-3330 should prioritize immediate credential changes and service disablement as primary actions. Network administrators must disable Telnet services entirely and migrate to more secure protocols such as SSH for remote administration. The default administrative accounts should be either disabled or have their passwords changed to strong, unique values that are not shared across multiple devices. Regular security audits should verify that default accounts remain disabled and that all network devices have been properly configured according to security best practices. Additionally, network segmentation and monitoring should be implemented to detect unauthorized access attempts and provide early warning of potential exploitation attempts, as this vulnerability can be detected through network traffic analysis and intrusion detection systems that monitor for Telnet connections to affected devices.