CVE-2018-6213 in DIR-620
Summary
by MITRE
In the web server on D-Link DIR-620 devices with a certain customized (by ISP) variant of firmware 1.0.3, 1.0.37, 1.3.1, 1.3.3, 1.3.7, 1.4.0, and 2.0.22, there is a hardcoded password of anonymous for the admin account.
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Analysis
by VulDB Data Team • 02/20/2020
The vulnerability identified as CVE-2018-6213 affects D-Link DIR-620 wireless routers running specific firmware versions that have been customized by Internet Service Providers. This represents a critical security flaw that undermines the fundamental authentication mechanisms of the device, creating an exploitable condition that allows unauthorized access to administrative functions. The issue manifests through a hardcoded credential configuration that persists across multiple firmware iterations, indicating a systemic design flaw rather than a transient software bug.
The technical implementation of this vulnerability involves a hardcoded password value of "anonymous" being embedded within the firmware code for the administrator account. This approach directly violates security best practices and represents a clear violation of the principle of least privilege as outlined in the OWASP Top Ten security framework. The hardcoded credential exists at the application level within the web server component of the router's firmware, making it accessible through standard network reconnaissance and exploitation techniques. This flaw falls under CWE-798, which specifically addresses the use of hardcoded passwords and credentials in software applications.
The operational impact of this vulnerability extends beyond simple unauthorized access, creating a significant attack surface that can be exploited by malicious actors to gain complete control over affected network devices. Once an attacker successfully authenticates using the hardcoded credentials, they can modify network configurations, install malicious firmware, redirect traffic, or establish backdoor access points. The vulnerability affects multiple firmware versions including 1.0.3, 1.0.37, 1.3.1, 1.3.3, 1.3.7, 1.4.0, and 2.0.22, indicating that the issue has persisted across several iterations of the device's software lifecycle. This widespread impact suggests that the vulnerability was not properly addressed through firmware updates, leaving organizations and consumers exposed to persistent threats.
Network security professionals should recognize this vulnerability as a prime example of how supply chain security can be compromised through ISP-customized firmware. The attack vector is straightforward and can be automated using standard penetration testing tools, making it particularly dangerous for environments where these devices are deployed without proper network segmentation or monitoring. The exploitation of this vulnerability aligns with techniques documented in the MITRE ATT&CK framework under the credential access and privilege escalation domains, specifically targeting the use of default credentials as an initial access method. Organizations should implement immediate mitigation strategies including network segmentation, disabling unnecessary services, and conducting comprehensive inventory audits to identify all affected devices. The vulnerability demonstrates the critical importance of proper credential management and the necessity of avoiding hardcoded values in security-sensitive applications as recommended by industry standards and best practices.