The Trojans are distributed through CAPTCHAs with instructions. Clicking the “I’m not a robot” button [for example] copies the line powershell.exe -eC bQBzAGgAdABhA<…>MAIgA= to the clipboard and displays so-called “verification steps”:

• Press Win + R (this opens the Run dialog box);
• Press CTRL + V (this pastes the line from the clipboard into the text field);
• Press Enter (this executes the code).

Malicious use of the system clipboard seems to be the popular choice, these days. If you fall for this, maybe the internet isn’t the place for you, just yet.