It's technically possible, as HDMI is a bidirectional interface. however, it is designed for packet streams, and not data blocks. LG would have to be down right unethical to configure it's HDMI ports to do something like that. If you don't have your LG smart tv connected via Ethernet or WiFi you're fine.
I've got an LG "smart" TV and like others here, do not have it connected to my network for just this reason. The only reason I even bought one with all the gadgets is because it seems that is about all that's available anymore with a decent amount of input options (usually basic HDTVs have just one or two HDMI inputs, no optical, no VGA-PC, etc.). I stream from my PS3 for Netflix and surf with a tablet or laptop in the living room. Any flash update needed will be done with a USB drive with the update downloaded to it from LG's support page.
I too have one of these LG Smart TV and got it connected to the Internet. After reading this not anymore. I did notice it was giving me mini ADs on the TV's home page and didn't think too much of it since I also use the OTA guide to see what is on my local stations. I use Roku and PS3 for streaming anyway. Now it even sends out filenames right off the USB...or even right off your DLNA server!!
Good job LG. Love your products but hate the fact you also invade our privacy so putting a block on my hardware firewall to keep it from spying on me anymore. Shame on you LG!
LOL @anyone who believes a 404 error means they didn't get your data. That error is just for show. Does their policy state they will collect your FILENAMES? I understand data you enter or approve, but collection of filenames on personal drives NOT part of your TV seems excessive (no it IS excessive and invading my private viewing habits). You're saying you have rights to anything and everything I may hook to the tv and not just your own data? Use your firewall or your router to kill this (block the mac or if that isn't possible set IP to static and block that etc). Many ways to kill this.