What class of attacks use innovative attack tools and once a system is infected it silently extracts data over an extended period?

Advanced persistent threat.

Explanation:

Advanced persistent threat is a threat actor implemented by either a government supported or private group to intrude a network or system and stays undetected, collecting information over a period of time.

It is used by cyber terrorist group to facilitate massive attacks based on the information retrieved. National or government group use the concept to promote national security.

what am i matchin tho

answerstandard;