Solomon Nasser landed in the repair shop when he ran into trouble with his smartphone.
"It just basically stopped working," said Nasser.
The problems had also spread to his computer.
"Well, they both picked up a virus when I downloaded an app, a free app, from the Internet," said Nasser.
Consumer Reports just tested 16 Android security apps designed to keep your smartphone or tablet safe.
"These apps protect you against online threats like viruses and malware, and they also help you, if your phone is lost or stolen, to remotely lock it or find it or wipe it," said Dean Gallea from Consumer Reports.
Testers checked to see how well each app protects a user's privacy and also assessed extras the apps have to offer.
"We looked at the apps' ease of use and also their versatility, including such features as being able to back up your phone or parental controls," said Gallea.
While some of the apps cost as much as $40 a year, you don't have to pay for good mobile protection.
"It turns out you can't go by price, because some of the best apps we tested were free, and some of the lower-rated ones were the more expensive ones," said Gallea.
In fact, one of the best is free. It's the AVAST Software Mobile Security and Antivirus app. It has nice features like parental controls, automatic backup, and an alarm you can activate if your device goes missing. It shouts out "This phone has been lost or stolen!"
iPhones are less susceptible to viruses and malware because Apple's store is the only source for apps. There have been few reports of any problems. However, no phone is immune to theft. If you have an iPhone, you can use the "Find My iPhone" feature to locate your phone on a map or remotely lock or delete all data to prevent a thief from accessing your information.