Do not trust websites promoting the "Mac OS Alert" scam

Also Known As: Mac OS Alert pop-up
Type: Mac Virus
Distribution: Low
Damage level: Medium

How to remove "Mac OS Alert" scam from Mac?

What is the "Mac OS Alert" scam?

"Mac OS Alert" is a scam, promoted on various deceptive websites. This scheme claims that visitors' devices may be infected and recommends a quick scan. The fake scan then comes up with several nonexistent viruses and states that the anti-virus suite has to be updated. It must be emphasized that no webpage can actually detect threats/issues present on systems; hence, any that make such proclamations - are scams. Schemes of this kind are designed to promote a variety of untrustworthy or even dangerous software. These scams commonly promote various potentially unwanted applications (e.g. fake anti-viruses, adware, browser hijackers, etc.) and in some cases they even proliferate malware (e.g. trojans, ransomware, etc.). Few users access deceptive sites intentionally, most access them via mistyped URLs, redirects caused by intrusive advertisements or by PUAs (Potentially Unwanted Applications).

Mac OS Alert scam

When a website running the "Mac OS Alert" scam is accessed, it displays several pop-up windows. The foremost pop-up informs visitors that their Macs may be infected. To detect the supposed viruses, the scam recommends users to scan their devices. The fake scan will take 10 seconds. To perform the scan and continue, visitors are told to click "OK" to continue. Once this window is closed, the background pop-up states that users' devices are supposedly infected with five viruses. Immediate action is required - the anti-virus software must be updated. Visitors are urged to update their anti-virus suites by clicking "Proceed", followed by "Download" on the next page - to install the latest updates. As mentioned in the introduction, all of the information provided by "Mac OS Alert" is false; i.e. the threats detected by this scheme are fake and merely used as bait to trick users' into downloading/installing and/or purchasing the promoted products. To summarize, by trusting the "Mac OS Alert" scam, users can experience system infections, severe privacy issues, financial losses and even identity theft.

Scams like "Mac OS Alert" typically promote various PUAs. These applications tend to appear legitimate and harmless; they may even be disguised as genuine existing products. Fake anti-virus tools are amongst the most popular apps endorsed in this fashion. Illegitimate anti-viruses require activation (i.e. purchase) to perform the advertised functions, yet even after activation - they remain nonoperational. Some PUAs can force-open unreliable, deceptive and malicious sites. Adware-types run intrusive advertisement campaigns, i.e. deliver various pop-ups, banners, coupons and other ads. They diminish the browsing activity, as they overlay page content and slow down the browsing speed. Once clicked on, intrusive adverts redirect to dangerous websites and some can even stealthily download/install software. Another PUA type called browser hijackers make modifications to browser settings in order to promote fake search engines. Hence, every new browser tab/window opened and web search done via the URL bar - redirect to the address of the promoted web searcher. Illegitimate search engines are seldom able to generate search results, so they tend to redirect to Google, Yahoo, Bing and other genuine ones. Browser hijackers can also restrict/deny access to the browsers' settings and/or undo any permitted changes made. What is more, most PUAs (regardless of type) can track data. They monitor browsing activity (URLs visited, pages viewed, search queries typed, etc.) and collect sensitive information extracted from it (IP addresses, geolocations and other details). The gathered data usually contains personally identifiable information. In summary, presence of unwanted software on devices endangers device integrity and user integrity. Therefore, it is strongly advised to remove all suspect applications and browser extensions/plug-ins immediately upon detection.

Threat Summary:
Name Mac OS Alert pop-up
Threat Type Phishing, Scam, Mac malware, Mac virus
Fake Claim Scam claims users' devices are infected and their anti-viruses are outdated.
Related Domains online-virus-scan[.]best
Detection Names (online-virus-scan[.]best) Netcraft (Malicious), Full List (VirusTotal)
Promoted Unwanted Application Various dubious applications
Serving IP Address (online-virus-scan[.]best)
31.31.198.236
Symptoms Your Mac becomes slower than normal, you see unwanted pop-up ads, you are redirected to dubious websites.
Distribution methods Deceptive pop-up ads, free software installers (bundling), fake Flash Player installers, torrent file downloads.
Damage Internet browser tracking (potential privacy issues), display of unwanted ads, redirects to dubious websites, loss of private information.
Malware Removal (Mac)

To eliminate possible malware infections, scan your Mac with legitimate antivirus software. Our security researchers recommend using Combo Cleaner.
▼ Download Combo Cleaner for Mac
To use full-featured product, you have to purchase a license for Combo Cleaner. Limited three days free trial available.

"Your system is heavily damaged by Two viruses!", "Your Apple iPhone is severely damaged by 19 viruses!", "Your Mac is infected with 5 viruses!" and "Check-apple-for-cleaning" are some examples of other scams similar to "Mac OS Alert". The Internet is rife with various deceptive websites, they use different models to trick visitors into trusting them. Common variants include: warnings that the device is infected and/or at risk, alerts that an essential software product is out-of-date, fake prize giveaways and raffles, unbelievable offers and deals, etc. Regardless of what scams claims, offer, request of demand, the end-goal is always the same - to generate revenue for the scammers / cyber criminals. Therefore, it is highly recommended to exercise caution when browsing.

How did potentially unwanted applications install on my computer?

Select PUAs have "official" download webpages, which are often promoted by deceptive/scam sites. These applications are also distributed via download/installation setups of other programs. This false marketing method of packing ordinary software with unwanted or malicious additions - is called "bundling". Rushed download/installation processes (e.g. ignored terms, skipped steps and sections, etc.) increase the risk of inadvertently allowing bundled content into the system. Intrusive adverts proliferate PUAs as well. Once clicked on, the ads can execute scripts to make stealthy downloads/installations.

How to avoid installation of potentially unwanted applications?

It is advised to research software prior to download/installation and/pr purchase. Only official and verified download channels must be used. Since untrustworthy download sources, e.g. unofficial and free file-hosting websites, Peer-to-Peer sharing networks and other third party downloaders - commonly offer harmful and/or bundled content. When downloading/installing, it is recommended to read terms, explore all available options, use the "Custom/Advanced" settings and opt-out from supplementary apps, tools, functions and other additions. Intrusive advertisements appear legitimate, however they redirect to questionable webpages (e.g. gambling, pornography, adult-dating, and so on). In case of encounters with such ads and/or redirects, the system must be checked and all suspicious applications and browser extensions/plug-ins detected - immediately removed from it. If your computer is already infected with PUAs, we recommend running a scan with Combo Cleaner Antivirus for macOS to automatically eliminate them.

Screenshot of a browser notification promoting the "Mac OS Alert" scam:

Notification promoting Mac OS Alert scam

Appearance of "Mac OS Alert" scam (GIF):

Appearance of Mac OS Alert scam (GIF)

Instant automatic Mac malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced computer skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of Mac malware. Download it by clicking the button below:
▼ DOWNLOAD Combo Cleaner for Mac By downloading any software listed on this website you agree to our Privacy Policy and Terms of Use. To use full-featured product, you have to purchase a license for Combo Cleaner. Limited three days free trial available.

Quick menu:

Video showing how to remove adware and browser hijackers from a Mac computer:

Potentially unwanted applications removal:

Remove potentially unwanted applications from your "Applications" folder:

mac browser hijacker removal from applications folder

Click the Finder icon. In the Finder window, select "Applications". In the applications folder, look for "MPlayerX","NicePlayer", or other suspicious applications and drag them to the Trash. After removing the potentially unwanted application(s) that cause online ads, scan your Mac for any remaining unwanted components.

Remove mac os alert pop-up related files and folders:

Finder go to folder command

Click the Finder icon, from the menu bar. Choose Go, and click Go to Folder...

step1Check for adware-generated files in the /Library/LaunchAgents folder:

removing adware from launch agents folder step 1

In the Go to Folder... bar, type: /Library/LaunchAgents

removing adware from launch agents folder step 2
In the “LaunchAgents” folder, look for any recently-added suspicious files and move them to the Trash. Examples of files generated by adware - “installmac.AppRemoval.plist”, “myppes.download.plist”, “mykotlerino.ltvbit.plist”, “kuklorest.update.plist”, etc. Adware commonly installs several files with the same string.

step2Check for adware generated files in the /Library/Application Support folder:

removing adware from application support folder step 1

In the Go to Folder... bar, type: /Library/Application Support

removing adware from application support folder step 2
In the “Application Support” folder, look for any recently-added suspicious folders. For example, “MplayerX” or “NicePlayer”, and move these folders to the Trash.

step3Check for adware-generated files in the ~/Library/LaunchAgents folder:

removing adware from ~launch agents folder step 1


In the Go to Folder bar, type: ~/Library/LaunchAgents

removing adware from ~launch agents folder step 2

In the “LaunchAgents” folder, look for any recently-added suspicious files and move them to the Trash. Examples of files generated by adware - “installmac.AppRemoval.plist”, “myppes.download.plist”, “mykotlerino.ltvbit.plist”, “kuklorest.update.plist”, etc. Adware commonly installs several files with the same string.

step4Check for adware-generated files in the /Library/LaunchDaemons folder:

removing adware from launch daemons folder step 1
In the Go to Folder... bar, type: /Library/LaunchDaemons

removing adware from launch daemons folder step 2
In the “LaunchDaemons” folder, look for recently-added suspicious files. For example “com.aoudad.net-preferences.plist”, “com.myppes.net-preferences.plist”, "com.kuklorest.net-preferences.plist”, “com.avickUpd.plist”, etc., and move them to the Trash.

step 5 Scan your Mac with Combo Cleaner:

If you have followed all the steps in the correct order you Mac should be clean of infections. To be sure your system is not infected run a scan with Combo Cleaner Antivirus. Download it HERE. After downloading the file double click combocleaner.dmg installer, in the opened window drag and drop Combo Cleaner icon on top of the Applications icon. Now open your launchpad and click on the Combo Cleaner icon. Wait until Combo Cleaner updates it's virus definition database and click "Start Combo Scan" button.

scan-with-combo-cleaner-1

Combo Cleaner will scan your Mac for malware infections. If the antivirus scan displays "no threats found" - this means that you can continue with the removal guide, otherwise it's recommended to remove any found infections before continuing.

scan-with-combo-cleaner-2

After removing files and folders generated by the adware, continue to remove rogue extensions from your Internet browsers.

Mac OS Alert pop-up removal from Internet browsers:

safari browser iconRemove malicious extensions from Safari:

Remove mac os alert pop-up related Safari extensions:

safari browser preferences

Open Safari browser, from the menu bar, select "Safari" and click "Preferences...".

safari extensions window

In the preferences window, select "Extensions" and look for any recently-installed suspicious extensions. When located, click the "Uninstall" button next to it/them. Note that you can safely uninstall all extensions from your Safari browser - none are crucial for normal browser operation.

  • If you continue to have problems with browser redirects and unwanted advertisements - Reset Safari.

firefox browser iconRemove malicious plug-ins from Mozilla Firefox:

Remove mac os alert pop-up related Mozilla Firefox add-ons:

accessing mozilla firefox add-ons

Open your Mozilla Firefox browser. At the top right corner of the screen, click the "Open Menu" (three horizontal lines) button. From the opened menu, choose "Add-ons".

removing malicious add-ons from mozilla firefox

Choose the "Extensions" tab and look for any recently-installed suspicious add-ons. When located, click the "Remove" button next to it/them. Note that you can safely uninstall all extensions from your Mozilla Firefox browser - none are crucial for normal browser operation.

  • If you continue to have problems with browser redirects and unwanted advertisements - Reset Mozilla Firefox.

chrome-browser-iconRemove malicious extensions from Google Chrome:

Remove mac os alert pop-up related Google Chrome add-ons:

removing malicious google chrome extensions step 1

Open Google Chrome and click the "Chrome menu" (three horizontal lines) button located in the top-right corner of the browser window. From the drop-down menu, choose "More Tools" and select "Extensions".

removing malicious Google Chrome extensions step 2

In the "Extensions" window, look for any recently-installed suspicious add-ons. When located, click the "Trash" button next to it/them. Note that you can safely uninstall all extensions from your Google Chrome browser - none are crucial for normal browser operation.

  • If you continue to have problems with browser redirects and unwanted advertisements - Reset Google Chrome.

About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Removal Instructions in other languages
Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

QR Code
Mac OS Alert pop-up QR code
A QR code (Quick Response Code) is a machine-readable code which stores URLs and other information. This code can be read using a camera on a smartphone or a tablet. Scan this QR code to have an easy access removal guide of Mac OS Alert pop-up on your mobile device.
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