In addition to application programs, the operating system (firmware) of ICS components can be changed. This can enable manipulated software to enter the system. Internal memory could be changed by an attacker by means of a compromised programming device, a local data interface (e.g. USB), or any other existing network connection. A software update might also have been manipulated along its path from the manufacturer to the operator. Ultimately, the operator might receive an ICS component whose firmware has already been compromised— for example, in the event of a manipulated supply chain or in procuring components from insecure sources. As a consequence, an attacker may modify or falsify processes and procedures.