Android has already come pretty far since it first appeared to the public in 2008. It's become one of the most popular mobile operating system in the planet, but it seems that its still relatively far from being perfect.
According to a report by CNET, researchers have identified a design flaw within Android that lets hackers do some pretty nefarious damage. The flaw allows apps to push a particular app into the foreground, allowing it to hijack whatever app you are running, and can be programmed to disable the back button.
Instances that the CNET article gave were bogus login screens that can steal your data, and an even more sinister and possible scenario -- targeted pop-up ads. The worse part is users won't be notified when the (potentially rogue) function kicks in.
The researchers who discovered this flaw have already alerted Google to this flaw, and have been told the company will look into it without losing the legitimate uses of the function. Google also pointed CNET towards an app that uses this function, which CNET cited as AppLock, by Visidon.