Years back I purchased a cheapskate ELM327, comes with a small DVD with drivers.
These drivers and apps were crowded with vira, as the chinese dealer had downloaded from the web and copied to the "driver" DVD.
If you do a search on these drivers, they are still around, containing virus.
Another common issue is looking for car schematics and service manuals.
If you find any of these outside official manufacturer sites, they are almost guaranteed to contain virus and trojans, hidden inside the rar file.
Windows Defender is IMHO the best upgrade Microsoft did to to their Windows OS.
It really needs more respect in public opinion, as it is there to protect you, and it is automatically updated.
Unless you disable that feature.
However it does not protect against trojans .. yet.