What is defined as a prolonged and focused cyberattack where an intruder steals information over an extended period?

A prolonged and focused cyberattack where an intruder steals information over an extended period is best defined as an Advanced Persistent Threat (APT).

APTs are characterized by their stealthy nature and long-term strategies employed by attackers to infiltrate a network and maintain continued access. Unlike other types of cyber incidents, APTs involve multiple stages that include initial reconnaissance, exploitation, sustained presence, and data exfiltration. This allows attackers to remain undetected while they gather sensitive information over time, which is typically the ultimate goal of such operations.

In contrast, cyber espionage refers more broadly to the act of spying to gather secrets or data, but it doesn’t necessarily imply the prolonged nature associated with APTs. A data breach is a more general term that indicates unauthorized access to data but does not imply the sustained attack vector characteristic of APTs. Lastly, malware attacks can happen quickly and often do not have the same level of persistence; they are typically singular events aimed at causing immediate harm or taking advantage of system vulnerabilities without the lengthy presence inherent to APTs.