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Remove Weknow virus from Chrome/Safari/Firefox on Mac

4 min read
Weknow is a piece of prolific malware plaguing Mac computers and causing browser redirects, so find out how to get around its persistence and remove it.
  1. What is Weknow virus?
  2. Remove Weknow virus from Mac manually
  3. Restore web browser settings to their original defaults
  4. Remove Weknow virus from Mac using a security suite

What is Weknow virus?

The Mac threat landscape is becoming increasingly heterogeneous over time. Whilst there is an abundance of existing perils out there, this environment is dominated by adware apps and fake optimizers. Meanwhile, it’s not very common to see a tandem of these two categories in action. The infection called Weknow is a rare case where fully-fledged browser hijack activity is combined with a drive-by promotion of scareware. Its “couple” is a notorious program known as MacKeeper, which has been a major headache for Mac fans for years. The main goal of the Weknow virus, though, is about twisting one’s web surfing experience. It embeds a malicious add-on in Safari, Google Chrome and Mozilla Firefox without permission and thereby forces hits to Weknow.ac site. This is a bogus search provider whose objective is to forward the traffic further to a service crammed up with ads.

Rogue search provider pushed by Weknow Mac virus
Rogue search provider pushed by Weknow Mac virus

The attack follows a fairly straightforward logic. First, the user unknowingly allows the culprit to gain a foothold on the Mac machine. This happens in the course of a software installation event that involves bundling. For those uninitiated, such a tactic denotes the infiltration of unwanted items into a system as part of a package. The catch is in the way the setup client is configured – it may appear to streamline the installation of a single app while not clearly disclosing that there are additional components tailgating inside as well. As a result, a routine of installing benign freeware, such as a video game, Adobe Flash Player update or movie downloader, may lead to contamination with the hijacker under analysis. It’s always more reasonable to choose the custom setup option over recommended one in such cases, because the potentially unwanted extra elements will at least be visible that way. As soon as the Weknow virus enters a Mac, it adds a new entry to the Login Items without consent so that the computer launches the harmful process at boot time. Having established persistence through suchlike manipulations, the infection turns the functioning of the browsers upside down.

MacKeeper scareware download page linked-to at Weknow.ac
MacKeeper scareware download page linked-to at Weknow.ac

A serious issue about the Weknow malware is that it supports all popular web browsers. Consequently, no matter if you prefer the native Safari or Mac versions of Chrome or Firefox, the impact is going to be the same. The rogue extension or plugin will alter the default Internet settings, including favorite search provider, start page and new tab page. These changes take effect beyond the victim’s awareness, which aligns with the shadiest of malware practices. The tweaking of browser behavior entails the redirects that cause the most frustration to those infected. Visiting Weknow.ac web page becomes a recurrent drag that accompanies every Internet navigation session, from browser launch to any attempt to do online search. It turns out, the site itself is just a starting point of the rerouting. Any search query returns results via a different dodgy service, such as webcrawler.com. The second-stage traffic forwarding instance is inundated with sponsored stuff above the fold, which is the number one lure for the operators of this malicious wave.

Speaking of the scareware promotion mentioned above, the Weknow.ac website contains a button that says “Clean Your Mac”. When clicked, it takes the user to a download page for the MacKeeper rogue program. If the victim falls for the claims about the pseudo benefits of the app and installs it, they run the risk of catching another cyber disease that will add up to the whole nuisance. The pest will forge Mac scans and return deceptive results full of inexistent memory hogs and security problems, with the purpose being to get its license sold. Keep in mind that MacKeeper doesn’t belong in your system and it won’t improve or fix anything, which isn’t broken in the first place. Zooming back into the Weknow Mac virus issue, not only does it irritate users and push a must-avoid application but it also poses a risk to privacy. The underlying plugin gathers the victim’s web browsing information, including Internet history, saved bookmarks, submitted forms, and account credentials. Such a multi-vector threat is certainly on nobody’s wish list, so go ahead and remove it now.

Remove Weknow virus from Mac manually

If you are okay with manual troubleshooting, use the following steps to uninstall the Weknow rogue app from your Mac. Be advised the persistence mechanisms employed by the infection may prevent this technique from being ultimately effective. One way or another, here’s the workflow:

• Open the Utilities directory under the Go menu in your Mac’s Finder.Go to Utilities on Mac

• When on the Utilities pane, select Activity Monitor (the Mac equivalent of Task Manager).Open Activity Monitor

• Once the Activity Monitor screen appears, check the list of running processes for an item you don’t recognize. Highlight that entry and click on the Quit Process option (button with the X symbol on it). The system will respond to this action with a confirmation dialog, where you should select Force Quit.Terminate malicious process in Activity Monitor

• Now go back to your desktop, expand the Go menu and pick Applications in the drop-down.Go to Mac Applications

• Spot the suspicious entry under Applications, right-click it, and select the Move to Trash option. Your Mac may request your administrator password at this point – enter it if that’s the case.Remove unwanted application from Mac

• Next, go to the Apple menu and choose System Preferences in the drop-down as shown below.Go to System Preferences

• Proceed to Users & Groups and select Login Items. Your Mac will display the list of apps that are executed automatically at boot time. Find the unwanted entry on that list and click on the “-” (minus) button down at the bottom.Delete app from login items

• While on the System Preferences screen, select Profiles. Spot the suspicious configuration profile and click the “-” (minus) button.Remove evil configuration profile

• Move on to the Go drop-down menu in the Finder and click the Go to Folder option.Go to Folder feature on Mac

• When the folder search box appears, enter the following path in it: ~/Library/LaunchAgents and click Go.Go to ~/Library/LaunchAgents

• Having accessed the LaunchAgents folder, look for suspicious items in it and, if found, send them all to the Trash.Delete unwanted LaunchAgents

• Follow the same logic to browse to folders named /Library/LaunchAgents (no tilde prepended), /Library/LaunchDaemons, and ~Library/Application Support. Look for potentially unwanted objects and send them to the Trash once spotted.

When done with the manual process of Weknow removal, take your time and check if the virus has vanished from your Mac. If it continues to cause browser redirects, move on to the following section of this tutorial.

Restore web browser settings to their original defaults

In the circumstances of a complex browser hijack like this, executing a reset makes the most sense despite a few obvious downsides. Customizations such as saved passwords, bookmarked pages etc. will be gone, but so will all the changes made by the potentially unwanted program. The instructions below address the workflow for the web browsers most targeted by the Weknow.ac virus.

Clean up Safari

• Go to the Safari menu and select Preferences.Safari preferences

• When on the Safari Preferences screen, select the Privacy tab and hit the Manage Website Data button if you are up to erasing all website data stored on your Mac (this is recommended in the SearchMarquis hijack situation).Manage Website Data in Safari

• A dialog will appear, asking you to validate your choice. Click the Remove All button if you are sure. Be advised that this will log you out of online services and undo personalized web browser settings such as saved passwords, etc.Confirm removal of all website data in Safari

• With Safari opened, click Develop in the Finder bar and select Empty Caches.Empty Caches in Safari

• Expand the History menu in the Finder area and click Clear History at the bottom of the list.Clear History in Safari

• Keep the all history option selected (it’s the default one) and click Clear History.Clear all history

• Restart Safari.

Reset Google Chrome

• Click Customize and control Google Chrome (⁝) in the upper right-hand part of the window and select Settings. Another way is to type chrome://settings in the URL bar and press Enter.Go to Settings in Chrome

• Move on to the Advanced area under Settings.Click ‘Advanced’

• Find the Reset settings subsection and click the Restore settings to their original defaults link within it.

• The browser will display a popup dialog asking if you are sure you want to restore settings to their original defaults. Confirm by clicking Reset settings.Confirm resetting Chrome

• Restart Chrome.

Reset Mozilla Firefox

• Open Firefox, type about:support in the URL area and press Enter. Alternatively, you can go to Help - Troubleshooting InformationGo to Troubleshooting Information in Firefox

• Click on the Refresh Firefox button and confirm the changes.Refresh Mozilla Firefox on Mac

• Restart Firefox.

Remove Weknow virus from Mac using a security suite

The most effective way to curb increasingly sneaky and persistent Mac threats is to use trusted security software. The award-winning Intego Mac Premium Bundle X9 is one of the best options across the anti-malware spectrum.

Its VirusBarrier component boasts a high detection rate and an outstanding cleaning capability. Additionally, the product comes packed with online security, optimization, and data backup features. Follow the steps below to use this sure-shot removal method.

1. Download Intego Mac Premium Bundle X9 installer and run it. The setup client’s prompts will walk you through the installation.

Download Weknow virus removal tool

Intego Mac Premium Bundle X9 installation

2. Open Launchpad from your Dock and select the just-added VirusBarrier app. Open VirusBarrier from Launchpad

3. Click the Full Scan button to have your Mac checked for security issues. Start a full scan

4. The first full scan may take 10 minutes or more, depending on the size of your disk. VirusBarrier will keep you informed about the number of files it has already checked. Full scan in progress

5. When the scan is through, the app will display a report that provides a summary of the detected malicious items and the total number of files checked. Click Select All and then Quarantine to move the threats to an isolated environment so that they can no longer harm your system. Scan report

6. Click the Quarantine tab in the upper toolbar and examine the files listed there. If you are sure all of them are malicious (which is most likely the case), click Repair All to completely eradicate these items from your Mac. Quarantined items

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