Computer hackers have taken to stealing data the easy way–by eavesdropping on phone and email conversations to find the keys to seemingly impregnable networks, security experts say. The danger of attacks with insider information was illustrated earlier this month with the arrest of a California man accused of breaking into mobile phone network T-Mobile’s database and reading emails and files of the U.S. Secret Service, and by the exploits of a hacker who breached a hospital’s database and changed mammogram results.