NETGEAR DGN2200 dnslookup.cgi Remote Command Execution Vulnerability Analysis and Mitigation Guide (CVE-2017-6334)

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2017-6334) is an OS command injection flaw located within the dnslookup.cgi script of the NETGEAR DGN2200 web management interface. The root cause lies in the lack of proper input validation and sanitization of the host_name parameter passed via HTTP POST requests. When the device processes a DNS lookup diagnostic request, it directly concatenates user input into a system shell command without escaping shell metacharacters (such as ;, &, or |), leading to arbitrary command execution.

2. Exploitation Mechanics & Attack Scenario

To exploit this vulnerability, an attacker must first authenticate to the router's web management portal using valid credentials (which may be obtained via default credentials or credential stuffing). Once authenticated, the attacker sends a crafted HTTP POST request targeting dnslookup.cgi. By embedding malicious payloads like ; telnetd -p 23 & inside the host_name parameter, the web server executes the injected command under root privileges, allowing the attacker to spawn a reverse shell or enable persistent backdoor access.

3. Infrastructure & Business Impact

As a CISA KEV-listed vulnerability with a high EPSS score, this flaw is actively exploited in the wild by threat actors to recruit devices into IoT botnets. Successful exploitation grants full administrative control over the router. This allows attackers to perform lateral movement within the internal network, conduct Man-in-the-Middle (MitM) attacks, hijack DNS traffic to redirect users to malicious sites, and compromise sensitive corporate data flowing through the network.