Computer users have often been warned to be wary of opening unsolicited email attachments because of the risk of malware infection, and yet many continue to be infected via precisely this method.
In other words, the malicious hackers attempting to infect your PC don’t need to take advantage of any zero-day exploits in your software, all they need to do is concoct the right camouflage for their email to fool you into clicking without thinking.
