Learn in the textbookAttacks on Web Applications
DefinitionA drive-by download (ドライブバイダウンロード) is an attack that infects a user with malware (malicious programs) without their knowledge, simply because they opened a web page.
ExplanationThe attacker plants malicious code in advance, either on a legitimate site they have tampered with or on a trap site of their own. When the user opens the page, a vulnerability (a security weakness) in the browser or a plug-in (an add-on to the browser) is exploited, and infection happens even without actions such as opening a file. The main defense is to update the OS and browser so that their vulnerabilities are closed.
AnalogyIt is like walking past a house and having a parcel tossed over the wall at you, though you never went through the gate. The parcel arrives whether or not you did anything to accept it.
Memory hook"Drive-by" means done while passing in a car. Just passing by, which here means merely viewing a page, is enough to be hit.