CVE-2018-20674 in DIR-850L C1
Summary
by MITRE
D-Link DIR-822 C1 before v3.11B01Beta, DIR-822-US C1 before v3.11B01Beta, DIR-850L A* before v1.21B08Beta, DIR-850L B* before v2.22B03Beta, and DIR-880L A* before v1.20B02Beta devices allow authenticated remote command execution.
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Analysis
by VulDB Data Team • 04/26/2020
This vulnerability affects multiple D-Link router models including DIR-822 and DIR-850L series devices running specific firmware versions. The issue stems from inadequate input validation within the web management interface that allows authenticated users to inject and execute arbitrary commands on the affected devices. The vulnerability exists in the command execution handling mechanism where user-supplied parameters are not properly sanitized before being passed to system commands. This authentication requirement means that an attacker must first obtain valid credentials to exploit the vulnerability, though this does not make the attack significantly more difficult as many users employ default or weak credentials. The affected models represent a range of consumer and small office routers that are widely deployed in residential and business environments. The vulnerability falls under the CWE-77 category of Command Injection, which is a well-documented weakness in software systems where untrusted data is directly incorporated into command execution contexts. From an operational perspective, this vulnerability presents a significant risk as it allows for complete system compromise once an attacker gains access to the device. The remote execution capability means that attackers can potentially gain persistent access to network infrastructure, modify router configurations, redirect traffic, or establish backdoors for future access. The impact extends beyond individual device compromise as these routers often serve as gateways for entire networks, making them attractive targets for attackers seeking to establish footholds within larger network environments. The vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically focusing on the execution of system commands through web interfaces. Network defenders should note that the attack surface is relatively limited since the vulnerability requires authentication, but the persistence and escalation potential make it a critical concern for network security teams. The affected firmware versions indicate that this was a known issue that required firmware updates to resolve, highlighting the importance of regular firmware maintenance for network infrastructure devices. Organizations should prioritize patching these devices as soon as firmware updates become available, as the vulnerability can be exploited by attackers who have obtained valid user credentials through various means such as credential reuse, phishing attacks, or default credential exploitation. The vulnerability demonstrates the importance of implementing proper input validation and output encoding in web applications, particularly those that interact with system-level commands. Security best practices recommend that all user inputs be treated as untrusted and properly sanitized before being processed by the application. The presence of this vulnerability in multiple models suggests that it may be a systemic issue in the firmware development process, indicating potential gaps in security testing and code review procedures. Network administrators should consider implementing network segmentation to limit the potential impact of such compromises, ensuring that even if a router is compromised, the attacker cannot easily move laterally within the network infrastructure. The vulnerability also underscores the need for robust authentication mechanisms and credential management practices to prevent unauthorized access to network devices.