DNS Spoofing

Allowing external control of DNS settings can lead to a disruption of service or unexpected application behavior.

DNS Spoofing, also known as DNS Cache Poisoning, is a type of attack in which an attacker corrupts the DNS resolver's cache, leading it to return incorrect IP addresses. Using DNS spoofing, an attacker can redirect users to malicious websites without their knowledge. In the context of server-side JavaScript using Node.js, improper handling of DNS server settings can lead to security vulnerabilities.

Example 1: Consider a scenario where a Node.js application enables users to specify custom DNS servers. If this input is not properly validated and sanitized, an attacker can supply malicious DNS servers and implement DNS spoofing attacks.

const dns = require('dns');

// User-controlled input for DNS servers
const customDnsServers = from_user_controlled_input;

// Set custom DNS servers
dns.setServers(customDnsServers);

In this example, the customDnsServers variable is assigned a value derived from user-controlled input. This input is then used to set the DNS servers using dns.setServers(customDnsServers). If an attacker provides malicious DNS server addresses, they can direct the application to resolve domain names using their servers, which can return false IP addresses.