Most, but not all. No one in my house visits adult websites and yet we got some weird malware on the computer that was causing the computer to do wacky things. I downloaded the free trial of malwarebyes and got rid of it.
As someone else posted, there is STILL a free version of Malwarebytes available. However, if all you use is the free version of Malwarebytes for your protection, you will soon be able to be giving away malware....ie.... you will be infected.
And, you do not need to get the trial of malwarebytes, the free version alone is good enough.
Not true since I'm the only one using my computer and I still get it. I heard it can come from music sites, sweepstakes and even news stories you click on - very frustrating!
Malware can come from anywhere. The New York Times and Forbes for example were serving up malicious ads not that long ago.
No matter what anti-malware software you use it is the last resort, not the first defense. The user is the most important anti-malware component of your computer. If you are using a Windows PC do not run as an administrator. Run as a normal user and only escalate your credentials when it is needed.
I run as a standard user, have Microsoft Security Essentials, block Flash by default, don't have Java installed at all, run the full MRT scan at least monthly, and run Spybot at least monthly. I also block third party cookies and ads for both privacy and as a form of defense.
Lastly, if you have any "smart" devices or IoT run them on a completely segregated network from your computer network.
The only difference is the premium protects in real time. With the free one you have to download the updates, initiate the scan and repair. I use it all the time.
Definitely not just adult websites. Malware can come from ads that are placed on virtually any kind of site, to the extent that it even infects sites like Forbes and the NYT. On top of this, you'd be surprised what kind of sites teens/kids visit to try and install games or watch movies. These are almost always hosted on what you'd call "adult" sites, sites that allow you to host files or link to sites that host files.
I am an I.T. professional and can't come up with any reason to pay for anti-virus for a personal computer. There is nothing you get extra that is worth it, they just come bloated with "features" that don't actually enhance your protection.
In an enterprise you are paying for real-time intrusion detection monitoring, centralized management, decoupling of sole responsibility to align with regulatory compliance, and of course most free anti-virus software is not licensed for the enterprise.
By all means continue to buy Norton if you feel it gives you extra protection but if you would like to save some money you don't have to. If you do want to spend money on something that does increase your protection go with something like a pfSense firewall.
In addition to AdBlock, which I highly recommend, I also run Disconnect and uBlock Origin in Firefox. I also did a lot of customization in about:config to make sure weak cyphers are turned off but that is a more advanced configuration that I know a lot of people aren't comfortable with.