While trojans and email phishing still feature prominently in hacker toolkits, getting into a system IRL is one of the most effective methods a truly determined hacker can use. Using a USB firewall could be your best defense.
More than likely, your computer automatically trusts any USB device that’s plugged into it. Hackers can use malicious code that’s injected to the USB’s drivers that will compromise a system.
In the case of the Stuxnet virus that temporarily sabotaged Iran’s nuclear program, it was brought into Iran’s Natanz nuclear facility on a thumb drive by an Isreali double agent. Russia was able to break into a classified network by distributing virus-filled USB drives at retail kiosks around NATO headquarters in Kabul. Eventually, the right employee bought one and plugged it into the system that was completely unconnected to the internet.
Not everyone is running a classified server or a nuclear program, so a USB firewall might be a bit of overkill for some. But who hasn’t bought a…