Removable media propagation is a malware delivery technique that uses USB drives, external disks, memory cards, or similar portable devices to move malicious code from one system to another. It is especially useful when attackers want to reach segmented or air-gapped networks that have limited or no internet access.
In cyber security, this matters because removable media often bypasses network controls that would stop email, web, or remote-access attacks. Once an infected device is plugged in, malware can execute automatically, copy itself to new machines, or wait for a user to open a decoy file. Defenders look for blocked autorun behavior, endpoint alerts on new USB devices, device control policies, and strict scanning of removable storage. In espionage and industrial environments, this technique is a common bridge for moving tooling into restricted systems where normal command-and-control traffic is difficult or impossible.