(NBC News) A recent Consumer Reports survey of more than 1,600 adult smartphone users found nearly 40 percent don't bother to take the minimal steps to secure them with simple password protection.
Experts warn that failure is putting personal information at risk.
"Your phone is like a master key to your bank account information, to your social networks, to just so many different things," warns Verizon's Wade Baker. "If you don't put a lock on that, as soon as you lose your phone and somebody swipes the screen, they have access to basically everything you've done."
Malicious software on smartphones, usually getting there through infected apps, is another smartphone security issue the survey highlighted.
"We project that 5 to 6 million people had symptoms on their phones last year of malicious software," says Consumer Reports Technology Editor Jeffrey Fox.
The Consumer Reports survey also addressed children and smartphones, saying 5 million preteens use them and may unwittingly disclose personal information.