PARIS (AP) — The leak of what purports to be a National Security Agency hacking tool kit has set the information security world atwitter — and sent major companies rushing to update their defenses. The tool kit consists of a suite of malicious software intended to tamper with firewalls, the electronic defenses protecting computer networks. The auctioneers claim the tools were stolen from the Equation Group, the name given to a powerful collective of hackers exposed by antivirus firm Kaspersky Lab in 2015. Nicholas Weaver, a researcher at the International Computer Science Institute in Berkeley, California, said that the news was terrible for the NSA no matter the circumstances behind the leak because companies like Cisco guard critical U.S.