Q: How to stop ads from popping up in a new window?

It's malware coming from MPlayerX that you should completely remove.

Uninstalling Software: The Basics

Most OS X applications are completely self-contained "packages" that can be uninstalled by simply dragging the application to the Trash.  Applications may create preference files that are stored in the /Home/Library/Preferences/ folder.  Although they do nothing once you delete the associated application, they do take up some disk space.  If you want you can look for them in the above location and delete them, too.

Some applications may install an uninstaller program that can be used to remove the application.  In some cases the uninstaller may be part of the application's installer, and is invoked by clicking on a Customize button that will appear during the install process.

Some applications may install components in the /Home/Library/Applications Support/ folder.  You can also check there to see if the application has created a folder.  You can also delete the folder that's in the Applications Support folder.  Again, they don't do anything but take up disk space once the application is trashed.

Some applications may install a startupitem or a Log In item.  Startupitems are usually installed in the /Library/StartupItems/ folder and less often in the /Home/Library/StartupItems/ folder.  Log In Items are set in the Accounts preferences.  Open System Preferences, click on the Accounts icon, then click on the LogIn Items tab.  Locate the item in the list for the application you want to remove and click on the "-" button to delete it from the list.

Some software use startup daemons or agents that are a new feature of the OS.  Look for them in /Library/LaunchAgents/ and /Library/LaunchDaemons/ or in /Home/Library/LaunchAgents/.

If an application installs any other files the best way to track them down is to do a Finder search using the application name or the developer name as the search term.  Unfortunately Spotlight will not look in certain folders by default.  You can modify Spotlight's behavior or use a third-party search utility, EasyFind, instead.

Some applications install a receipt in the /Library/Receipts/ folder.  Usually with the same name as the program or the developer.  The item generally has a ".pkg" extension.  Be sure you also delete this item as some programs use it to determine if it's already installed.

There are many utilities that can uninstall applications.  Here is a selection:

    1. AppZapper

    2. AppDelete

    3. Automaton

    4. Hazel

    5. AppCleaner

    6. CleanApp

    7. iTrash

    8. Amnesia

    9. Uninstaller

  10. Spring Cleaning

For more information visit The XLab FAQs and read the FAQ on removing software.

Helpful Links Regarding Malware Problems

If you are having an immediate problem with ads popping up see The Safe Mac » Adware Removal Guide and The Safe Mac » Adware Removal Tool.

Open Safari, select Preferences from the Safari menu. Click on Extensions icon in the toolbar. Disable all Extensions. If this stops your problem, then re-enable them one by one until the problem returns. Now remove that extension as it is causing the problem.

An excellent link to read is Tom Reed's Mac Malware Guide.

Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.

See these Apple articles:

  Mac OS X Snow Leopard and malware detection

  OS X Lion- Protect your Mac from malware

  OS X Mountain Lion- Protect your Mac from malware

  OS X Mavericks- Protect your Mac from malware

  About file quarantine in OS X

If you require anti-virus protection Thomas Reed recommends using ClamXAV. (Thank you to Thomas Reed for this recommendation.)

From user Joe Bailey comes this equally useful advice:

The facts are:

1. There is no anti-malware software that can detect 100% of the malware out there.

2. There is no anti-malware that can detect everything targeting the Mac.

3. The very best way to prevent the most attacks is for you as the user to be aware that

     the most successful malware attacks rely on very sophisticated social engineering

     techniques preying on human avarice, ****, and fear.

4. Internet popups saying the FBI, NSA, Microsoft, your ISP has detected malware on

    your computer is intended to entice you to install their malware thinking it is a

    protection against malware.

5. Some of the anti-malware products on the market are worse than the malware

    from which they purport to protect you.

6. Be cautious where you go on the internet.

7. Only download anything from sites you know are safe.

8. Avoid links you receive in email, always be suspicious even if you get something

    you think is from a friend, but you were not expecting.

9. If there is any question in your mind, then assume it is malware.

Lando53 wrote:

 

I recently downloaded MPlayerx and now whenever I am on a website and click on a tab, an add pops up in a new window. Is this a virus, if so how do I get rid of it? or what do I have to do to get this to stop? I deleted the app and went into applications and deleted that also but it keeps happening.

It's not MPlayerX, it was caused by something that came with it from the place where you downloaded it. The one I got from the developer's site http://www.mplayerx.org/ has never been a problem. To find out how this happened and how to avoid it in the future see John Galt's How to install adware.

To get rid of the adware run TheSafeMac's Adware Removal Tool for safest, most efficient removal of most currently known adware.

You may have installed the "VSearch" trojan, perhaps under a different name. Remove it as follows.

Malware is constantly changing to get around the defenses against it. The instructions in this comment are valid as of now, as far as I know. They won't necessarily be valid in the future. Anyone finding this comment a few days or more after it was posted should look for more recent discussions or start a new one.

Back up all data before proceeding.

Triple-click anywhere in the line below on this page to select it:

/Library/LaunchAgents/com.vsearch.agent.plist

Right-click or control-click the line and select

          Services ▹ Reveal in Finder (or just Reveal)

from the contextual menu.* A folder should open with an item named "com.vsearch.agent.plist" selected. Drag the selected item to the Trash. You may be prompted for your administrator login password.

Repeat with each of these lines:

/Library/LaunchDaemons/com.vsearch.daemon.plist
/Library/LaunchDaemons/com.vsearch.helper.plist
/Library/LaunchDaemons/Jack.plist

Restart the computer and empty the Trash. Then delete the following items in the same way:

/Library/Application Support/VSearch
/Library/PrivilegedHelperTools/Jack
/System/Library/Frameworks/VSearch.framework
~/Library/Internet Plug-Ins/ConduitNPAPIPlugin.plugin

Some of these items may be absent, in which case you'll get a message that the file can't be found. Skip that item and go on to the next one.

From the Safari menu bar, select

          Safari ▹ Preferences... ▹ Extensions

Uninstall any extensions you don't know you need, including any that have the word "Spigot," "Trovi," or "Conduit" in the description. If in doubt, uninstall all extensions. Do the equivalent for the Firefox and Chrome browsers, if you use either of those.

Reset the home page and default search engine in all the browsers, if it was changed.

This trojan is distributed on illegal websites that traffic in pirated content. If you, or anyone else who uses the computer, visit such sites and follow prompts to install software, you can expect much worse to happen in the future.

You may be wondering why you didn't get a warning from Gatekeeper about installing software from an unknown developer, as you should have. The reason is that this Internet criminal has a codesigning certificate issued by Apple, which causes Gatekeeper to give the installer a pass. Apple could revoke the certificate, but as of this writing, has not done so, even though it's aware of the problem. This failure of oversight has compromised both Gatekeeper and the Developer ID program. You can't rely on Gatekeeper alone to protect you from harmful software.

*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination  command-C. In the Finder, select

          Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.