Issues with uploads of SeaMonkey created html files

[kwqd33]

Starting today, I am unable to upload any of my existing html files to my public_html directory, even files that were created in 2013, haven't been opened or modified since and which I already uploaded to x10 around that year. I am running Ubuntu Linux 18.04.1 with all current patches. It doesn't seem to matter which browser I open my x10 session in, Chrome, FireFox or SeaMonkey. I created a couple of small html files using gedit and they uploaded fine as do image files (.jpg, etc.). I believe that all of the existing files that I tried to upload were created with some version of SeaMonkey.

Here is the error that I am getting.

The file you uploaded, art.html, contains a virus so the upload was canceled: Can't create temporary directory ERROR

I was a linux admin for 17 years and not aware of any viruses that could have infected all of the html files on my system, so a bit perplexed. I was also a UNIX/Linux security admin for 5 years so don't do anything that could compromise my system. The only thing I have done recently was to update SeaMonkey from 2.49.2 to 2.49.4, but I've been running SeaMonkey for quite some time and done quite a few upgrades with no issue. I am just a user on my home machine, no development, scripting, etc...

Is anyone else having similar issues or does anyone have any suggestions?

thanks.

 

[kwqd33]

UPDATE: I keep a backup of this computer on an air gapped laptop and it has been a few weeks since I made a backup to it so pretty certain whatever I suspected was impacting this computer was not affecting the laptop. I copied the backup file art.html from that laptop to a USB drive and then copied the file from the USB drive to this computer, after first running a "diff" against the file on the USB drive and the file on the computer. There were no differences between the two files. I tried up loading art.html again from this computer to my public_html folder and got the same virus message. Next I tried uploading it from the USB drive and it uploaded successfully with no virus warning. At this point I started to suspect that my system had been compromised, so I shut it down and connected my laptop to the network, changed my important passwords and did some research. I was able to upload all of the files from my laptop that x10 had flagged as being contaminated by a virus.

I could not find data about any exploit like this, though. I next disconnected my laptop from the network again and powered this computer up to do some more analysis. The first thing I did was to send an email attaching one of the files x10 had flagged as containing a virus from my Yahoo email client to another email client hosted by my domain hoster and from the email client of my domain hoster to Yahoo mail and both arrived with no virus flags. Yahoo and my domain hoster both scan email attachments for viruses. I next opened a new session with x10 and I am now able to successfully upload all of the files that x10 flagged as containing a virus with no issues. Hmmmmm. At this point, I am guessing the issue was on x10's side, maybe they were dealing with a large scale virus attack just rejecting specific types of html files(?). No idea what happened and can't explain why I was able to upload a supposedly virus infected file from a USB drive connected to the computer, but not from the computer hard drive. Weird.