Learn in the textbookMalware Basics and Major Infection Types
DefinitionA computer virus (コンピュータウイルス) is malware that attaches its own code to other programs or files and uses them as a foothold to spread infection.
ExplanationA virus cannot run on its own; it starts running only when the file it has attached to, its host (a document file or program), is opened or run. Some viruses get in by exploiting a vulnerability (脆弱性), a weakness in the design or build of an OS or application, and in that case applying the security patch (セキュリティパッチ) that closes the weakness prevents infection.
AnalogyA biological virus cannot multiply until it gets inside a cell, and a computer virus likewise cannot multiply without a host file.
Memory hookThe word virus comes from a Latin word meaning “poison.”