Apple recently responded to a known security issue in iOS that has been dubbed "Masque Attack." In its simplest form, the attack can be used by would-be hackers to try to trick an end user into installing dangerous malware on his or her iPhone.

It takes advantage of the iOS Enterprise Developer platform, which allows enterprise departments to distribute apps to employees outside of the Apple iTunes App Store. That can be dangerous, since Apple typically advises you only install apps directly from the store.

"We designed OS X and iOS with built-in security safeguards to help protect customers and warn them before installing potentially malicious software," Apple told iMore recently. "We're not aware of any customers that have actually been affected by this attack. We encourage customers to only download from trusted sources like the App Store and to pay attention to any warnings as they download apps. Enterprise users installing custom apps should install apps from their company's secure website."

There's not much else to it: you can completely avoid any security issues if you just make sure you're installing apps from a trusted source. In other words: don't go downloading an app someone emails you about.