Computer hacking really results in financial losses and hassles. The objectives of terrorist groups are more serious. That is not to say that cyber groups can't access a telephone switch in Manhattan on a day like 9/11, shut it down, and therefore cause more casualties.
Kevin MitnickSocial engineering is using manipulation, influence and deception to get a person, a trusted insider within an organization, to comply with a request, and the request is usually to release information or to perform some sort of action item that benefits that attacker.
Kevin MitnickOracle, for example, has even hired people to dumpster dive for information about its competitor, Microsoft. It's not even illegal, because trash isn't covered by data secrecy laws.
Kevin Mitnick