Attackers can still conceal their point of origin by looping or leap-frogging several computer systems in several countries before finally going into the system that is being attacked as well as those pursuing them.

CENTERFORSECURITYPOLICY: The silent cyberwar

Media outlets including The New York Times, The Wall Street Journal and The Washington Post have all said this year that their computer systems were breached, while several NBC websites were briefly hacked in November.

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However, classified computer systems were compromised in the past using several methods.

CENTERFORSECURITYPOLICY: Center For Security Policy