In a Windows 10 guest under VirtualBox in Ubuntu 17.10 I downloaded a PDF file and got two files:
<filename>.pdf # as expected
<filename>.pdf:Zone.Identifier:$DATA # ??
The second file has a size of 26B and has the following contents:
[ZoneTransfer]
ZoneId=3
What is this second file and why do I get it? Is it perhaps related to the SharedFolder of Virtualbox?