The Secret Life of Smartphones: Who has your information and where it's going

SAN FRANCISCO (KGO) -- Did you know that your smartphone is leading a double life?

Whether it's sending your text, charging on your nightstand, or tucked away in your pocket, your phone is busy-- even when you're not.

"It doesn't shut off when you shut off," said Patrick Jackson, a former NSA researcher and chief technology officer for Disconnect, a San Francisco-based startup that's working to stop companies-- all those apps you download-- from tracking you online.

"It's always good to know what's going on, on your phone," explained Jackson before he hooked up ABC7 news reporter Kate Larsen's iPhone to special software to find out where her data is going.

First, Jackson examined popular real estate app, Redfin, and said his software showed that Redfin was sending data from Larsen's phone to Facebook.

"Before Redfin even calls its own servers, Facebook is first in line to send data off your device, back to Facebook."

That may explain all those very tailored, sometimes invasive-feeling, ads that pop up in your Facebook feed.

Jackson also checked the Yelp, Songkick and Rent The Runway apps, all of which were feeding information about Larsen and her phone to Facebook and third-party trackers.

The worst offender was a flashlight app. Jackson explained that the simplest apps can sometimes be the most dangerous.

"They're almost like Trojan horses. They come in there with one purpose, but then they do all this stuff in the background and you see that there's tons of tracking because it's just a cesspool of, this is a free app and we need to try and monetize it as many ways as possible and they know data is just one of those ways they can monetize."

Jackson says even if someone doesn't have a Facebook account or Facebook app on their phone, apps can still pass along your data to the social media giant.

Jackson's list of objections to data trackers is long. But bottom line, he does not trust them, since he does not believe they are built with the consumer's safety in mind.

"What they do with that information, we don't know."

To keep your data more secure, Jackson recommends deleting unnecessary and unused apps. iPhones come with an Apple flashlight app, so the third party flashlight app on Larsen's phone was redundant and potentially unsafe, so she deleted it.

Jackson also recommends limiting your permission settings on your phone. Not every app needs location sharing to function properly.

iPhone users can also choose to limit ad tracking in settings.

There is also a free iOS version of Jackson's tracker blocker called Privacy Pro, that he says will help keep your data safe.

Jackson says Google won't allow Disconnect's Privacy Pro app into its Play Store for Android phones, because Google doesn't allow apps that might interfere with ad displays.