A URI, or Uniform Resource Identifier, is a standardized string used to identify a resource on a network. In web traffic, it often includes the path and optional query string after the host name, such as the specific endpoint an application or client is trying to reach.
In cyber security, URIs matter because they can stay stable even when domains change. Malware and command-and-control systems often rotate hostnames to avoid blocking, but reuse the same request paths, upload endpoints, or parameter patterns. Defenders can hunt for these URI structures in logs, proxies, and network sensors to spot malicious behavior. A suspicious URI is not proof of an attack by itself, but repeated or unusual paths combined with other signals can reveal malware activity, data exfiltration, or automated abuse.