PHOENIX — Is your phone running slower? Are you having to charge it more?
It could mean a failing battery or it could mean your phone is infected with a virus.
With about four billion smartphones out there, they've become a huge target for hackers.
They want to get into your phone, steal information, or watch where you go and what you do.
The warning signs include subtle changes as well as your phone running hotter than usual.
Data Doctors' Ken Colburn says most phone malware comes from app downloads.
Sticking with downloads from the Apple store and Google Play is safest. But, even those stores have had issues and removed dozens of apps found to have malware or codes that were unacceptable.
Colburn says before installing, look at the apps' number of reviews and downloads. He says apps with fewer ones don't mean it's bad, just untested.
"If there's another app that does the same thing and has way more downloads and reviews might be a better choice," Colburn said.
He also advises removing apps you don't use and not ignoring security updates.
Many times those updates patch holes found in the phone's security system.
Also, consider an app scanner that automatically looks for malware.
Google's "Playprotect" is built into the Google Play store and there are many others that offer free versions for Android and iPhones.
"A lot of them, once you install them, become active so that any new apps you try to install they'll do a quick review for you as well," Colburn added.
If you know your phone is infected, the last resort would be to reset it.
Colburn calls it the nuclear option because it will remove all apps, downloads, pics, and anything stored.
So, make sure you've backed it all up first.
Read more about smartphone malware on the Data Doctor's site.