How does malware get onto machines?

Attackers use a variety of techniques to get malware onto machines and sometimes employ more than one technique. The following are a few of the outlined techniques:

• Phishing: Email is the primary method used to propagate malware through various types of phishing campaigns. It can come in as an attachment or link to a malicious URL. Newer campaigns are using QR codes as a method to bypass some of the security controls defenders have relied upon to keep phishing emails out of the system.
• Physical media: Malware can be loaded onto USB flash drives by attackers who then wait for unwary victims to insert them into their computers. This isn’t very common, but it does happen. Another way is that any USB device connected to an infected machine could also become infected by the attackers’ virus, and then it infects any machine it is plugged into.
• Pop-up alerts: This includes phony security alerts that lure you into downloading...