First, check the website of the company offering the antivirus, especially if a brand you have not heard of is promoting a free antivirus download. Verify that the company is real and reputable, and if its website is safe and secure. Malicious websites or virus-infected applications and devices often offer fake or rogue antivirus software through pop-up ads. You can use a web protection service like the one included in McAfee Total Protection to help you avoid malicious websites.