Severity: Unknown
Description: The D-Link router DIR-868L 3.01 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.
CVSS Score: N/A
D
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1. Risk Assessment
The D-Link DIR-868L router running firmware version 3.01 is vulnerable to hardcoded credentials exposed through the telnet service. This means an attacker, without needing to authenticate, can decompile the firmware and discover credentials embedded within it. The nature of the vulnerability is a classic case of poor security practice – relying on hardcoded credentials instead of robust authentication mechanisms. The business impact could be significant. Successful exploitation can lead to full control of the router, potentially allowing attackers to monitor network traffic, change DNS settings, redirect users to malicious sites, or even gain access to the internal network. The likelihood of exploitation is moderate to high, as decompiling firmware is a relatively straightforward process, and many D-Link DIR-868L routers may still be running this vulnerable firmware version. The ease of exploitation is also moderate, requiring some technical skill but not necessarily advanced expertise. The impact on confidentiality is high, as sensitive network data and potentially user credentials could be compromised. Integrity is also at risk, as attackers can modify router configurations. Availability could be impacted if the attacker causes a denial-of-service condition or disrupts network connectivity. The EPSS score of 0.008320000 suggests a relatively low but non-negligible risk, indicating it’s worth addressing, especially for organizations reliant on the router’s functionality.
2. Potential Attack Scenarios
An attacker on the local network, or even remotely accessible through the internet if port 23 (Telnet) is exposed, can exploit this vulnerability. The attacker first connects to the router via Telnet. Next, they obtain a copy of the router’s firmware. Utilizing a firmware decompiler, such as binwalk, the attacker decompiles the firmware image. During decompilation, the attacker searches for commonly used usernames and passwords within the firmware code. They identify hardcoded credentials – likely for administrative access or other services running on the router. Finally, the attacker uses these credentials to log into the router’s web interface or via Telnet, gaining full administrative control. This control allows them to change DNS settings to redirect traffic through a malicious DNS server, enabling man-in-the-middle attacks, or to open up VPN tunnels for persistent access to the network.
3. Mitigation Recommendations
The primary mitigation is to upgrade the router firmware to a version that addresses the hardcoded credentials issue. D-Link should be contacted for the latest firmware version compatible with the DIR-868L. If an immediate upgrade isn't possible, consider disabling the Telnet service if it's not essential. This can be done through the router’s web interface. Implement strong passwords for any administrative accounts, even if Telnet is used. Regularly monitor router logs for suspicious activity and unauthorized access attempts. Consider segmenting the network to limit the impact of a compromised router. The following link provides further details on the vulnerability and exploitation: https://cybersecurityworks.com/zerodays/cve-2020-29321-telnet-hardcoded-credentials.html
4. Executive Summary
The D-Link DIR-868L router, version 3.01, contains hardcoded credentials that can be easily discovered by attackers through firmware decompilation. This vulnerability allows unauthorized access to the router, potentially compromising network security and user data. The risk is moderate, but the impact can be significant, ranging from network monitoring to full control of the router and access to the internal network. To mitigate this risk, we recommend upgrading the router firmware as soon as possible. If an upgrade is delayed, disable the Telnet service and implement strong passwords. Addressing this vulnerability is crucial to protecting our network and ensuring the confidentiality, integrity, and availability of our data. Prompt action will minimize the potential for disruption and data breach.