Stock, non-jailbroken iOS devices appear to be vulnerable to a new security threat; a trojan known as AceDeceiver, which can be installed on an iOS device without the user's knowledge and without the help of an enterprise certificate. Once installed, it will spread malware and unwanted software to the user's device.
AceDeceiver only seems to be affecting those located in China at this point in time, but because that could change on the fly, you need to know how to protect yourself so similar threats don't affect users across the globe in the future.