After being told hackers could easily gain access to vulnerable, unguarded devices, the U.S. Department of Homeland Security is recommending users to stop using the Universal Plug and Play, or UPnP, feature. The very common tool allows certain devices to communicate with each other over the internet, like a printer and a computer. A company called Rapid7 stated about 40 million to 50 million devices are vulnerable, allowing hackers to retrieve secure information.  [Source: Reuters]