Effective defenses against malware and other threats

Last modified: Mar 21, 2020 9:35 PM
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Questions regarding the use of "anti-virus" or similarly categorized "Internet security" products frequently arise on this site. Many of them are from new Mac users whose previous computer experience was limited to traditionally virus-prone Windows PCs. Early Microsoft Windows versions were notoriously vulnerable to unauthorized modifications and malicious interference, which gave rise to a cottage industry of "anti-virus" software companies responding to a need for the operating system security Microsoft neglected to provide.

Apple and Microsoft's respective operating systems were originally conceived and developed completely separately, for use with completely different hardware, and their evolution has only diverged since their inception. In recent years Microsoft has made great strides in protecting its Windows operating system, but owing to macOS's original concept as a multi-user, multitasking operating system incorporating a fundamental requirement to keep users separate from one another, it was never as vulnerable to begin with. With each new release, macOS has only grown more secure from unauthorized tampering.

It's important to understand the nature of threats that exist today, and to appreciate the fact that "anti-virus" software peddlers have been reduced to abject panic as their traditional Windows PC market suffers its inevitable decline. The cottage industry described in the first paragraph has since grown to a multi-billion dollar behemoth with entrenched interests—an enormous beast that demands to be fed. The PC market's demise has led to a predictable response from them and shills who represent their interests, asserting that since Macs are rapidly growing in popularity, they have become just as vulnerable to "viruses" as PCs, implying an even greater need for the products they sell. It just isn't so.

What is true is that the growing base of Mac users are being increasingly targeted and exploited for scams that seek to defraud them of their hard-earned money. Criminals who seek to do that cannot succeed without your help. Don't give them the satisfaction.

The following describes simple principles that will serve to protect your Mac, and yourself, from the various threats that exist today. It's long, but if you read nothing else, read the first three numbered points and the Summary at the end. They are equally applicable to Macs, PCs, mobile devices or anything else that uses software to communicate with the world beyond it.


There will always be threats to your information security associated with using any Internet - connected communications tool:

  1. You can mitigate those threats by following commonsense practices
  2. Delegating that responsibility to software is an ineffective defense
  3. Assuming that any product will protect you from those threats is a hazardous attitude that is likely to result in neglecting point #1 above.

macOS already includes everything it needs to protect itself from viruses and malware. Keep it that way with software updates from Apple.

Rather than asking which non-Apple "anti-virus" or "Internet security" product is best, a much better question is "how should I protect my Mac":

  • Never install any product that claims to "clean up", "speed up", "optimize", "boost" or "accelerate" your Mac; to "wash" it, "tune" it, or to make it "shiny". Those claims are absurd.
    • Such products are very aggressively marketed. They are all scams.
    • They generally operate on the flawed premise that a Mac accumulates "junk" that needs to be routinely "cleaned out" for optimum performance.
    • Trial versions of those programs are successful because they provide the instant gratification of greater free disk space.
    • That increased space is the result of irreversible destruction of files, programs, or operating system components normally protected from inadvertent alteration or deletion. The eventual result will be unreliable operation, poor performance and random crashes that may not become evident for months or even years after their use, when updates to programs or macOS are eventually released.
    • Memory "cleaners" that circumvent macOS's memory management algorithms work by purging inactive memory contents to mass storage, which can only result in degraded performance and accelerated hardware failure.
  • Never install pirated or "cracked" software, software obtained from dubious websites, or other questionable sources.
    • Illegally obtained software is almost certain to contain malware.
    • "Questionable sources" include but are not limited to spontaneously appearing web pages or popups, download hosting sites such as C net dot com, Softonic dot com, Software dot com, Soft Pedia dot com, Download dot com, Mac Update dot com, or any other site whose revenue is primarily derived from junk product advertisements.
    • If you need to install software that isn't available from the Mac App Store, obtain it only from legitimate sources authorized by the software's developer.
    • macOS helps prevent you from inadvertently installing software that may be malicious or untrustworthy. If macOS warns you about that, pay attention. It's important.
  • Don't supply your password in response to a popup window requesting it, unless you know what it is and the reason your credentials are required:
    • Your Apple ID and its password are the keys to your digital kingdom. Safeguard both of them just as you would your wallet or purse.
  • Don't open email attachments from email addresses that you do not recognize, or click links contained in an email:
    • Most of these are scams that direct you to fraudulent sites that attempt to convince you to disclose personal information.
    • Such "phishing" attempts are the 21st century equivalent of a social exploit that has existed since the dawn of civilization. Don’t fall for it.
    • Apple will never ask you to reveal personal information in an email. If you receive an unexpected email from Apple threatening to close your account unless you take immediate action, just ignore it. If your iCloud, iTunes, or App Store account becomes disabled for valid reasons, you will know when you try to buy something or log in to this support site, and are unable to.
    • A variant of the same scam takes the form of an emailed receipt for an iTunes Store or App Store purchase you did not make. The email will contain a link soliciting your Apple ID to confirm the alleged purchase. Both the link and the receipt are fraudulent.
  • Don't install browser extensions unless you understand their purpose:
    • Go to the Safari menu > Preferences... > Extensions. If you see any Extensions that you do not recognize or understand, simply click the Uninstall button and they will be gone.
    • No Safari Extensions are required for normal operation.
  • Don't install any Profiles unless your Mac is owned or controlled by your employer, school, or similar institution:
    • Profiles are commonly installed by institutions to ensure their Macs conform to their requirements.
    • To determine if a Profile is installed on your Mac, open (Apple menu) > System Preferences... > General.
    • If you see Profile pane and you have no explanation for its presence, you may have been deceived into installing it. Remove it by selecting it and clicking the [—] (minus) button.
  • Don't install Java or Flash unless you are certain that you need it:
    • Java, a non-Apple product, remains a potential vector for malware. If you are required to use Java, be mindful of that possibility.
    • Java can be disabled in System Preferences.
    • Despite its name JavaScript is unrelated to Java. No malware can infect your Mac through JavaScript. It's OK to leave it enabled.
    • The same precaution applies to Adobe Flash Player. Newly discovered Flash vulnerabilities occur almost weekly.
    • Flash Player's demise is as imminent as it is deserved. You can help accelerate that inevitable fate by not using it.
  • Don't rely upon Internet search engines to obtain technical support assistance:
    • Scam artists pay popular Internet search companies in exchange for greater prominence in search results, so their websites and contact information are given precedence over the legitimate companies they fraudulently claim to represent.
    • The overwhelming majority of web search results seeking instructions to remove unwanted software (for example) are just advertisements for even more unwanted software. Their "instructions" are designed to be difficult to follow, won't work, will make things worse, or all the above.
    • If you require technical support, determine the company's legitimate contact information from their own website or product literature, and initiate contact with them directly.
    • Support for all Apple products is obtained by using the Contact Support link at the top of this web page.
    • If you receive an unsolicited phone call from someone attempting to convince you a problem exists with your Mac, PC, or mobile device, it's a scam. Hang up.
    • Legitimate organizations such as Apple and Microsoft do not initiate contact in that manner.
  • Beware spontaneously appearing, unsolicited popups demanding immediate action. Think before you click.
    • Popup windows are useful and required for some websites, but unsolicited popups are commonly used to deceive people into installing unwanted software they would never intentionally install.
    • Ad-blocking Safari Extensions can help, but none are completely effective, and all of them can cause unexpected behavior.
    • If you encounter a website, text message, email, or phone call alleging your Mac is infested with some ick or that you need to take immediate action lest dire circumstances ensue, it is 100% fraudulent. Ignore it. Read Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams.
    • If you find Safari has frozen or "locked up", leaving you unable to dismiss the page, read Phony "tech support" / "ransomware" popups and web pages for the solution.
    • Any spontaneously appearing dialog insisting that you upgrade your video player right this instant should be summarily ignored. Such popups are commonly associated with sites that promise to deliver "free" movies, music, or other copyrighted content that is not normally "free", but no website that hosts interest-based targeted advertising is completely immune from that threat.
  • Ignore hyperventilating popular media outlets that thrive by promoting fear and discord with entertainment products arrogantly presented as "news". Learn what real threats actually exist and how to arm yourself against them:
    • The most serious threat to your data security is phishing. Most of these attempts are pathetic and are easily recognized, but that hasn't stopped prominent public figures from recently succumbing to this age-old scam.
    • macOS viruses do not exist, but intentionally malicious or poorly written code, created by either nefarious or inept individuals, is nothing new.
    • Never install something without first knowing what it is, what it does, how it works, and how to get rid of it when you don't want it any more.
    • If you elect to use "anti-virus" software, familiarize yourself with its limitations and potential to cause adverse effects, and apply the principle immediately preceding this one.
    • Most such utilities will only burden your Mac while they look for viruses that do not exist. They will degrade its performance and prevent it from working properly while conveying no benefit whatsoever—other than to make you "feel good" about security, when you should actually be exercising sound judgment, derived from accurate knowledge, based on verifiable facts.
  • Do install updates from Apple as they become available. No one knows more about Macs and how to protect them than the company that builds them.

Summary: Use common sense and caution when you use your Mac, just like you would in any social context. There is no product, utility, or magic talisman that can protect you from all the evils of mankind.


Selected reference material follows.

US Federal Trade Commission: http://www.consumer.ftc.gov/articles/0346-tech-support-scams

US FBI Internet Crime Prevention Tips: https://www.ic3.gov/preventiontips.aspx

Adware: How to install adware

Popups: Phony "tech support" / "ransomware" popups and web pages

Fraudulent "Flash Player Updates": Beware bogus Adobe Flash "installers"


Sep 1, 2018 2:16 PM

Force quit followed by Force reloading browsers in safe mode would be a good addition to this tip. Whether it is the option key or shift key, the safe reload of a web browser makes the blank home page load instead of the last page opened or home page in the browser preference. If someone gets a ransomware popup this procedure is the quickest way to get rid of it without introducing new Trojan horses.

Sep 1, 2018 2:16 PM

Nov 16, 2018 1:38 PM

Maybe add references to:

  • backups and depth of backups and off-site backups,as these are usually the least disruptive recovery path post malware and post-breach,
  • to the use of password managers and generated passwords, Keychain or otherwise,
  • to enabling multi-factor on Apple ID and otherwise,
  • to using ad blocking as a potential way to reduce the cruft increasingly arriving within our browser windows from sketchy and breached ad networks.

Current NIST guidelines around (not) making frequent password changes, and around using multi-factor, and longer passwords.


Current Safari on macOS has a very handy way of reporting re-used passwords. Safari preferences passwords, look for the warning triangles.

As for phishing, that’s evolving and some of the scams are ”clever”, and that often because of password re-use.

Sextortion Scam Uses Recipient’s Hacked Passwords — Krebs on Security

Nov 16, 2018 1:38 PM

Nov 28, 2018 5:50 PM

Those are all excellent additions, thanks!

Phishing in particular has become even more insidious. The "pathetic and easily recognized" attempts of the past are inexorably yielding to more sophisticated attempts. What's taken so long?

I will incorporate all your suggestions to the extent the impending ASC format changes will permit... and when I find the time (which isn't getting any easier... this late reply for example).

Nov 28, 2018 5:50 PM

Jun 5, 2019 5:50 AM

To amend my force quit tip:

  1. When you get a website that appears phony or tries to get you to buy tech support because of a presumed hack attack, force quit it. Use command (Windows key on non-Apple keyboards)-Option (Alt on non-Apple keyboards)-ESC (sometiems called escape) key combination to bring up the force quit window. Then select the browser (Chrome, Firefox, Safari) where the offending page showed up and click on force quit. Next time you open the browser hold the shift key. This allows you to avoid restoring the last browsing session, and start fresh.
  2. If your machine was compromised, you should test it with a known malware removal program that works well for the Mac. Both Malwarebytes and Avast do a pretty thorough job. Malwarebytes does not come with an uninstaller. If you use Malwarebytes remove it searching for all components with mbam using a product like Devon Technologies EasyFind. Only scan for viruses when you aren’t doing other tasks as it can take several hours. If you find no viruses nor malware are present, consult a Malware expert on Macs such as myself. I run a business and can take remote calls in the U.S. macmaps.com *
  • Links to my pages may give me compensation.

Jun 5, 2019 5:50 AM