### Comment:
How can malware infect a computer without the user's knowledge?

### REPLY:
One way malware can infect a computer without the user's knowledge is by exploiting zero-day vulnerabilities, which are vulnerabilities in software that are unknown to the software developer. By taking advantage of these vulnerabilities, malware can silently install itself on the computer. Another method is through rootkits, which are designed to hide the presence of malware by modifying the operating system. These techniques can allow malware to persist on a computer undetected by antivirus software.