If you use Window Defender as your antivirus tool, we recommend that you update it now. Details are here.
A vulnerability has been discovered that allows a worm to infect your computer, as Windows Defender scans the file to see if its infected. You do not need to open it, for it to infect your computers.
The fix is simple, open Windows Defender, click on the update tab then click on Update Definitions. Once it updates, this problem is fixed.
I highly recommended that you do this ASAP as I am sure right now these worms are being written and released.
Update 10/5/17: It appears that many other antivirus software has been updated yesterday, almost certainly for the same reason. I recommend that you upgrade your antivirus software ASAP.