As far as I know this site is as safe here as any other reputable file transfer method. I have faith that Autodesk wouldn't let anyone splicing anything bad into the stuff we download and other users would have to hack into the system to get that level of access. So no real worries on that end. That said, if someone uploaded an infected file to the site and you downloaded it then you're vulnerable - which is exactly the same with any other file transfer.
Now let's all go start out our week worrying about all those infected bits of code in dyf files that we've passed around like pink eye through a kindergarten!
Seriously though I can't stress this enough - it would be difficult and not worth the effort to attach malicious code to something on these forums. Not a wide enough distribution network. So don't worry about it on that front.
A virus (meaning self replicating malicious code) can attach itself to a dwg, rvt, dyf, jpg or any other file type though. That's why they are called viruses: they spread. But this is why we protect ourselves. Everyone here has heard about the need for antivirus and why when they bought their last personal computer, tablet or phone. Just because you're working in a corporate environment doesn't change that need. But the sad reality about antivirus is that it works like real medicine in that the 'vaccine' for a virus can't be put in place until we know what that virus is (imagine the next Polio, now go cure that before it exists).
This is why every office should have digital security measures in place (firewalls, antivirus, limited permissions, frequent data backups on separate media, etc). The severity and restrictions of these measures should be tailored to the work of your office (the neuclear plant should have more restrictions than a sole proprietor doing single family homes).
Ask your IT department, consultant, or the 'computer guy' in your office for specifics about your office's system. They won't have to go into too much technical detail for you to get the just of it. You will likely be surprised by what actually happens in the background while we do our documentation and design work. So much of what they do goes completely unnoticed until something breaks at which point they usually serve as the 'fall guy' for stuff that is out of their control.
There should really be a national 'IT support' day... someone call Hallmark I'm sure they would love a reason to sell more greeting cards.