CVE-2018-6210 in DIR-620
Summary
by MITRE
D-Link DIR-620 devices, with a certain Rostelekom variant of firmware 1.0.37, have a hardcoded rostel account, which makes it easier for remote attackers to obtain access via a TELNET session.
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Analysis
by VulDB Data Team • 02/20/2020
The vulnerability identified as CVE-2018-6210 affects D-Link DIR-620 wireless routers running specific firmware versions including the Rostelekom variant 1.0.37. This issue represents a critical security flaw that stems from the improper implementation of authentication mechanisms within the device's firmware. The vulnerability allows remote attackers to establish unauthorized TELNET sessions by leveraging a hardcoded administrative account that is embedded within the router's firmware code. This hardcoded credential presents a significant risk as it eliminates the need for attackers to perform password guessing or other reconnaissance activities to gain access to the device's management interface. The presence of such hard-coded credentials violates fundamental security principles and creates an inherent backdoor that remains accessible regardless of the device owner's configuration choices or security practices.
The technical implementation of this vulnerability involves the inclusion of a predetermined username and password combination directly within the firmware binary of the affected D-Link devices. When the router's TELNET service is enabled, which is often the case in default configurations, attackers can simply connect to the device using the hardcoded credentials to gain administrative privileges. This flaw specifically impacts the authentication mechanism and represents a direct violation of security best practices outlined in various industry standards including those referenced in the CWE database under CWE-798. The vulnerability is classified as a hardcoded credential issue where sensitive information is embedded within the software rather than being dynamically generated or securely stored, making it accessible to anyone who can access the device firmware or network services.
The operational impact of CVE-2018-6210 extends far beyond simple unauthorized access to a single device. Once an attacker gains administrative control of a router, they can manipulate network configurations, redirect traffic, install malicious software, or use the device as a pivot point to launch attacks against other systems within the network. This vulnerability particularly affects enterprise and home networks where the router serves as the primary gateway and security boundary. The attack surface is significantly expanded as the compromised device can be used to conduct man-in-the-middle attacks, DNS hijacking, or to create persistent backdoors within the network infrastructure. The implications are further compounded when considering that many users may not be aware that their router is compromised, leading to prolonged exposure and potential data breaches. This vulnerability aligns with ATT&CK techniques related to credential access and privilege escalation, specifically targeting the T1078 credential access tactic.
Mitigation strategies for CVE-2018-6210 require immediate action from device owners and network administrators. The primary recommendation involves updating the firmware to a version that removes the hardcoded credentials and implements proper authentication mechanisms. Device manufacturers should be contacted to obtain patched firmware versions specifically addressing this vulnerability. Network administrators should also consider disabling unnecessary services such as TELNET when they are not required for legitimate network management purposes. Additional security measures include implementing network segmentation to limit the potential impact of a compromised device, monitoring network traffic for suspicious TELNET connections, and ensuring that default credentials are changed immediately upon device deployment. The vulnerability highlights the importance of proper software supply chain security and the need for manufacturers to conduct thorough security testing before releasing firmware updates to the public. Organizations should also implement regular security audits and vulnerability assessments to identify similar hardcoded credentials in other network infrastructure devices.