How to Prevent and Remove Malware on Macs and PCs

March 15, 2016

by UNH IT Staff

MalwareMalware is portmanteau (two words combined to form a new word) for malicious software. It’s designed and intended to “damage or disable computers and computer systems.” (

Malware comes in all shapes and forms, and some are more harmful than others, but one thing is certain: preventing infections is critical to keeping your files and personal information safe.

Here are a few tips from the Academic Technology Support Center (ATSC) on preventing and removing software from your Mac or PC.

Preventing Malware

Common sources of malware include:

  • Clicking on ads/links
  • Facebook links/games/apps
  • Illegal file downloads (music, movies, software)
  • Freeware/web toolbars

To prevent malware infections:

  • Don’t click on ads.
  • Avoid websites with ads and pop-ups.
  • Don’t download programs you don’t trust.
  • Always read each screen of software installer packages; they often include freeware such as web browser toolbars
  • Update your computer software frequently

Common best practices include:

  1. Keep your operating software up to date.
  2. Keep your plug-ins up to date (Java, Flash, Adobe Reader, Silverlight).
  3. Ensure you have active antimalware/antivirus protection on your computer (instructions and downloads available at

Malware Removal

  1. Boot your machine into Safe Mode (PCs only). Do not choose Safe Mode with Networking.  

  2. Run CCleaner (PCs and Macs)

This free program is available online and has many great optimization features. While it doesn’t remove malware, it will uninstall superfluous programs with a user-friendly interface, and fixes issues related to the malware infection. It should be noted that while CCleaner is effective for Macs in regards to clearing out internet history and cookies, users can also clear their browser cache without installing this software (see below). Download CCleaner

  1. Run the Cleaner tab.
  2. Run the Registry tab.
  3. Use tools to uninstall malicious programs.
  1. Run Malwarebytes (PCs and Macs)

Malwarebytes is also freely-available and works great for removing malware. It’s similar to your antivirus software, but will only run when prompted. It also won’t prevent malware infections, but that also means it won’t interfere with your antivirus software without causing interference. Download Malwarebytes

  1. Restart your computer. (PCs and Macs)

If Malwarebytes didn’t find anything serious (Trojan, Rootkit), restarting should solve your remaining issues. After restarting, open your web browsers (Firefox, IE, Chrome) and make sure they don’t direct you to suspicious websites. Also-ensure all pop-up ads have stopped. If they have not, clear your browser cache (this article from Box has instructions for each web browser).

For questions or support, contact the UNH IT Service Desk at 603-862-4242, visit the AT Support Center (Dimond Library, third floor – main level), or visit the UNH IT Knowledge Base.

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