SAN FRANCISCO (KPIX 5) -- If you're considering selling, trading or donating an old cellphone, you may be handing over more than you think.
But there is a way to protect the data you think you've wiped from your phone.
From banking to shopping to private photos, our smartphones know a lot about us.
Saint Vincent College professor Anthony Serapiglia said, "It's a treasure trove for identity theft."
Serapiglia and his students found plenty of that sensitive information left behind on abandoned cellphones.
"We found lots of text messages, conversations, Snapchats, things that you thought should be gone but they are not gone. We will find them," Serapiglia said.
Using software that anyone can buy, Serapiglia and his students scanned phones purchased from Goodwill.
25 pounds of phones, purchased in bulk online for just $83. Of the 80 phones, more than half had useful information.
One damaged iPhone turned out to be filled with illegal activity.
Serapiglia said, "It had text messages of drug deals, prostitution and gambling."
One phone didn't come with a battery, but it did have its memory card.
Serapiglia said, "Thieves are trying to build a story around you so that they can impersonate you so they can open an account in your name and just make a good story."
His advice is always preform a factory reset before you part with your phone.
But don't stop there. Remove your SIM card and keep it safe. And always encrypt your data.
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