A video is about to start, but a verification screen appears first. It looks familiar: a checkbox, a security logo and a message asking to confirm that a real person is visiting. Most people have completed enough of these checks to follow the instructions without much thought.

Then comes an extra step. The page asks to open a Windows tool and paste a command. It sounds unnecessary, but the instructions are clear and the video is waiting. Following them can install malicious software instead of completing a security check.

This is a fake CAPTCHA scam. It uses a routine part of browsing to persuade people to do something they would normally avoid: run instructions from an unknown source. 阅读更多...