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

### REPLY:
One effective way to infect a computer without the user's knowledge is by using a Trojan horse. This involves disguising the malware as a legitimate file or program that the user willingly downloads and executes. Once the Trojan is executed, it can perform various malicious activities, such as stealing sensitive information or granting unauthorized access to the attacker.