When I clicked on the update request after opening WinSCP today, a browser widow opened which said I had a Trojan and should contact a certain number. I have not responded and closed the browser, but it needed Taskmanager to do it. It seems as if there is a malicious link in the update.
Its almost certainly related to the advertisements on the WinSCP download page that this person ran into. Those things usually have silly ads that do stuff like that.
If its not that then its a website, plugin, or something else with this person's browser previously, possibly Chrome or Chromium based as they tend to typically have that issue.
Ublock Origin browser plugin on non-Chromium browser generally should solve this users problem with that.
