The cyber kill chain is a model created by Lockheed Martin that splits a cyberattack into seven stages: reconnaissance, weaponization, delivery, exploitation, installation, command and control, and actions on objectives. It helps you see where an attack stands and break the chain as early as possible.
Related term in this glossary: MITRE ATT&CK
kill chain, Lockheed Martin kill chain, attack lifecycle, stages of a cyberattack