CVE-2018-20432 in COVR 3902 REVA
Summary
by MITRE
D-Link COVR-2600R and COVR-3902 Kit before 1.01b05Beta01 use hardcoded credentials for telnet connection, which allows unauthenticated attackers to gain privileged access to the router, and to extract sensitive data or modify the configuration.
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Analysis
by VulDB Data Team • 06/16/2024
The CVE-2018-20432 vulnerability affects D-Link COVR-2600R and COVR-3902 wireless routers, representing a critical security flaw that stems from improper credential management within the device firmware. This vulnerability specifically targets the telnet service implementation, which incorporates hardcoded authentication credentials that remain unchanged across all affected devices. The flaw exists at the application layer of the network stack, where the router's firmware fails to properly randomize or generate unique authentication tokens for remote access services, creating a persistent backdoor mechanism that persists across device reboots and factory resets.
The technical exploitation of this vulnerability follows a straightforward attack pattern that aligns with attack techniques documented in the MITRE ATT&CK framework under the T1075 credential access tactic. Attackers can simply connect to the telnet service using the hardcoded credentials without requiring any prior authentication or privilege escalation attempts. This allows unauthorized individuals to establish a privileged session with root-level access to the router's command shell, bypassing all standard authentication mechanisms. The vulnerability demonstrates a clear violation of security principle 3 from the NIST Cybersecurity Framework, specifically concerning the protection of system components through proper access control mechanisms.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it provides attackers with complete administrative control over the affected network infrastructure. Once authenticated, attackers can modify router configurations, implement persistent backdoors, monitor network traffic, and potentially use the compromised device as a pivot point for attacking other systems within the local network. The ability to extract sensitive data from the router's memory and configuration files creates additional risks for organizations relying on these devices for network security, as they may inadvertently expose network credentials, encryption keys, or other confidential information stored within the device's volatile memory.
The vulnerability's classification as a CWE-798 weakness under the Common Weakness Enumeration framework highlights the fundamental flaw in software development practices that incorporate hardcoded credentials into production firmware. This represents a critical design flaw that violates established security best practices and standards including those outlined in the OWASP Top Ten 2017, specifically addressing the risk of hard-coded credentials in applications and systems. Organizations utilizing these devices face significant risk of lateral movement within their networks, as the compromised router can serve as a launching point for more sophisticated attacks targeting internal systems, making the vulnerability particularly dangerous in enterprise environments where network segmentation may not be properly implemented.
Mitigation strategies for this vulnerability should include immediate firmware updates from D-Link to address the hardcoded credential issue, along with network segmentation to limit the potential impact of a successful compromise. Security professionals should implement network monitoring to detect unauthorized telnet connections and consider disabling telnet services entirely while enabling secure SSH alternatives. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all instances of affected hardware within their network infrastructure, as the hardcoded credentials create a persistent threat that remains viable across multiple device configurations and operating environments. The vulnerability serves as a reminder of the critical importance of secure development practices and the necessity of implementing proper credential management mechanisms in all network infrastructure devices.