CVE-2020-29322 in DIR-880L
Summary
by MITRE • 06/05/2021
The D-Link router DIR-880L 1.07 is vulnerable to credentials disclosure in telnet service through decompilation of firmware, that allows an unauthenticated attacker to gain access to the firmware and to extract sensitive data.
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Analysis
by VulDB Data Team • 06/10/2021
The CVE-2020-29322 vulnerability affects the D-Link DIR-880L router model running firmware version 1.07, presenting a critical security flaw in the telnet service implementation. This vulnerability stems from insufficient security measures in the router's firmware design, specifically within the telnet service that remains enabled by default. The flaw allows attackers to extract administrative credentials through firmware decompilation techniques, bypassing normal authentication mechanisms and creating a significant backdoor access vector.
The technical implementation of this vulnerability involves the exposure of hardcoded credentials within the firmware binary that can be reverse engineered through decompilation processes. Attackers can obtain the router's administrative password by analyzing the firmware image, which typically contains plaintext or weakly encrypted credentials stored in memory segments accessible through the telnet service. This approach aligns with CWE-312 (CWE-312: Cleartext Storage of Sensitive Information) and CWE-798 (CWE-798: Use of Hard-coded Credentials), both of which address the improper handling of sensitive authentication data in software systems. The vulnerability specifically impacts the router's network security posture by providing unauthorized access to the device's administrative interface without requiring legitimate authentication.
The operational impact of CVE-2020-29322 extends beyond simple credential theft, as it enables attackers to assume full administrative control over the affected router. Once credentials are obtained, attackers can modify router configurations, implement malicious network policies, redirect traffic through proxy servers, or establish persistent access points within the network. This vulnerability particularly affects enterprise and home networks where the router serves as a primary gateway, potentially allowing attackers to compromise entire network infrastructures. The threat landscape for this vulnerability aligns with ATT&CK technique T1078 (Valid Accounts) and T1566 (Phishing for Information), as it enables attackers to leverage legitimate administrative credentials for unauthorized access and data exfiltration.
Mitigation strategies for CVE-2020-29322 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific vulnerability. Network administrators should disable telnet services entirely and implement SSH as the primary remote administration protocol when possible. Additional defensive measures include network segmentation to limit access to administrative interfaces, implementation of intrusion detection systems to monitor for unusual telnet connections, and regular firmware audits to ensure all devices maintain current security patches. The vulnerability highlights the importance of secure firmware development practices and proper credential management in embedded systems, emphasizing the need for strong cryptographic implementations and the elimination of hardcoded credentials in network devices. Organizations should also consider implementing network access controls and monitoring for unauthorized administrative access attempts to detect potential exploitation of this vulnerability.