(CBS SF) – A report on Sunday night’s “60 Minutes” showed how hackers were able to access a California congressman’s smartphone, just by knowing the lawmaker’s phone number.

By day, Karsten Nohl’s security lab in Berlin advises Fortune 500 companies on computer security. At night, the international team of hackers tries to find flaws in everyday devices including smartphones, USB sticks and SIM cards.

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To test if Nohl’s group could do what it claimed, 60 Minutes sent an iPhone to Rep. Ted Lieu (D-California), who has a computer science degree from Stanford. He agreed to use the phone to talk to his staff, knowing they would be hacked. With the phone number, Nohl and his team was able to break in, record the congressman’s calls and track his movements.

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The hackers were able to exploit a flaw in Signaling System 7 (SS7), a little-known network that connects mobile phone carriers.

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