Cyber Glossary - Z

Zero-day Attack - A cyber exploit that relies on exploiting an unknown or undisclosed vulnerability in the design or implementation of a system to violate its security. SOURCE: Cyberspace Solarium Commission Final Report, 2020

Zero Fill – To fill unused storage locations in an information system with the representation of the character denoting "0." (CNSSI-4009) (NISTIR)

Zeroization – A method of erasing electronically stored data, cryptographic keys, and CSPs by altering or deleting the contents of the data storage to prevent recovery of the data. (SOURCE: FIPS 140-2) (NISTIR)

Zeroize – To remove or eliminate the key from a cryptographic equipment or fill device. (SOURCE: CNSSI-4009) (NISTIR)

To overwrite a memory location with data consisting entirely of bits with the value zero so that the data is destroyed and not recoverable. This is often contrasted with deletion methods that merely destroy reference to data within a file system rather than the data itself. (SP 800-63) (NISTIR)

Zombie – A program that is installed on a system to cause it to attack other systems. (SP 800-83) (NISTIR)

Zone of Control – Three-dimensional space surrounding equipment that processes classified and/or sensitive information within which TEMPEST exploitation is not considered practical or where legal authority to identify and remove a potential TEMPEST exploitation exists. (CNSSI-4009) (NISTIR)