It’s far more than semantics. Whether malware is a virus or trojan or other form of malware has a great effect on the defense required. A virus spreads without the user’s involvement or knowledge, so antivirus software is needed for protection. A trojan, on the other hand, can be avoided without requiring software, because the user has the option to not install it. Your posts indicate that you don’t understand that, so you, like other uninformed users, incorrectly use the terms “virus” and “malware” interchangeably.
You haven’t seen a Mac virus blocked by an antivirus app. You may have seen a Windows virus blocked (which would have no effect on a Mac), but not a Mac virus. Again, you’re making false statements.
Two problems with this statement. First, no one is saying Macs are safe from infections; only that they are safe from virus infections. Macs can be infected by other forms of malware, but all of them are easily avoided without antivirus apps and are relatively rare.
The second problem is the foolish notion that a Mac user should install antivirus apps to protect Windows users. First, many Mac anti-malware apps, such as MalwareBytes don’t even scan for Windows malware. Also, if you really want to do your Windows friends a favor, encourage them to install their own antivirus software. That way they’re protected from malware from all sources, not just from files you may send them. Otherwise, you haven’t really helped them.
Macs don’t get viruses. Period. That is not a myth, but a proven fact that neither you nor anyone else can prove otherwise. Macs CAN get viruses, but there are none to get, and never have been any in the past 17 years since OS X was introduced.
Macs can get other forms of malware, but it’s rare, and users can avoid all malware by practicing safe computing. Your two friends may be great network administrators, but that doesn’t mean they understand even basics about the Mac malware environment and by the fact that they didn’t practice safe computing to avoid infections to begin with.
If you really want to warn fellow Mac users with a balanced and accurate response, you should tell them the following.
Macs are not immune to malware and no system is 100% secure, but no true viruses exist in the wild that can run on macOS, and there never have been any since it was released over 17 years ago. Be clear about this:
Macs CAN get viruses, but they DON’T, because no true macOS virus exists in the wild. Understand that a virus is just one particular type of malware (malicious software) that, when executed, replicates itself by modifying other computer programs and inserting its own code. There has never been a macOS virus in the wild, but there are other types of malware.
Other forms of macOS malware (Trojans, worms, rootkits, etc.) in the wild can ALL be avoided by practicing safe computing, without requiring any antivirus or anti-malware apps to be installed.
Practicing safe computing means using common sense and staying informed.
Keep macOS and your apps updated at all times. Many of these updates include patches to vulnerabilities that can prevent attacks. If you have outdated software, your system may be more vulnerable.
Be careful about what you install on your Mac.
- Don’t install pirated software, from bit torrent sites or any other source.
- Don’t install anything without investigating to make sure that the app and the site you download it from have good reputations. Asking in this forum is a great way to learn what is safe and what isn’t.
- Do install apps from the Mac App Store.
- Do install apps directly from developer sites that have a good reputation.
- Pay attention when installing apps, to make sure you install only the app that you want, and not any unwanted add-on apps that may be bundled with it. If you need help, ask for it.
- Don’t let anyone else have access to your computer, and especially don’t let anyone else install something without your permission.
Use common sense when surfing the Internet. If you’re unsure about anything, ask in this forum or ask someone you know who is informed and experienced.
- Be extremely careful anytime you are asked for any password or any personal information, including your name, phone number or email address. Make sure you only enter that kind of information in an app or website that you are certain that you can trust.
- Install and use a reputable and effective ad blocker on your web browser
- Avoid shady websites, especially any that try to get you to download anything to install, such as a codec to enable your system to play a video.
- Only update your apps from within the app itself or from the Mac App Store.
- If you are surfing the web and see a message pop-up or receive an email saying that you need to install or update anything, be very suspicious and do not allow it. For example, if a site tells you that your Adobe Flash is outdated, do not update it from that site. Instead, go directly to the Adobe site to install the update.
- The same holds true for pop-up messages that tell you that your Mac is infected with viruses or malware. These are lies. No website can scan your Mac to find malware. These are all attempts to get you to buy something or install something that you shouldn’t. Don’t do it.
Adware is software designed to generate and display online advertisements on your computer. While not true malware, adware is usually unwanted and a nuisance, but it can easily be avoided by practicing safe computing (see above).
Antivirus and anti-malware apps are not required to keep a Mac malware-free, as long as a user practices safe computing. Some antivirus apps have themselves been used to introduce malware to Macs, so they can increase vulnerability. Many who have relied on antivirus apps and did not practice safe computing have had their systems compromised by threats that their antivirus app did not detect. No antivirus or anti-malware app has a 100% detection rate, but since Mac OS X (macOS) was introduced, practicing safe computing has effectively defended against 100% of macOS malware in the wild.
If you haven’t been practicing safe computing and you want to check your system for any malware you may have allowed to be introduced, use
MalwareBytes to scan your system. It’s free and doesn’t need to be continuously running. Just scan once and practice safe computing from this point forward.
In general, macOS malware is so relatively rare, that only a very small percentage of Mac users have ever encountered any.
If you really want to help your friends who use Windows, encourage them to install their own antivirus software, so they're protected from all potential sources of malware, not just from files you send them from your Mac.