A u.s. security claims its traced the most extensive cyber attacks in recent history to one chinese military unit in shanghai. according to the virginia based firm, it s likely operating out of a 12-story building of. hundreds of employees, breached more than 100 american organizations ranging from it and telecommunications to aerospace and energy. chinese officials strongly deny the accusations, even said we re doing it to them. u.s. officials wouldn t comment on the specifics of the report, but they have repeatedly expressed concerns about the growing cyber threat out of china. kathryn hecatherine herridge wis live from washington. what are we learning about the details? reporter: shep, this report is highly charged because it names names that the electronics