Dangerous Web Browser Extensions

Learn how to avoid them

(No time to read right now? Just want to see the list of things to know? Here you go.)

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Introduction

Browser extensions can be useful but they can also be dangerous. We'll explain what they are and how to know if they're safe to use.

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What are Browser Extensions?

Browser extensions (also called plugins or addons) are extra bits of functionality that can be added to a web browser.

They're like apps that run “inside” the browser.

They do things like block ads and trackers, show discount codes on shopping sites, let you take screenshots of web pages, manage your passwords, and many more things.

Sometimes they're created by the browser makers (Google, Mozilla, Apple, Microsoft, etc.) and sometimes they're built by 3rd-party developers.

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Are They Secure?

Browsers have built-in rules about what extensions are allowed (and not allowed) to do, so they'll generally prevent an extension from doing something bad.

Sometimes an earlier version of an extension is compliant, but an update violates the rules in a way the browser can't detect.

Extensions that don't connect to a remote server are generally safer to use than those that do connect (but this is hard to determine).

The problem is that remote servers can push viruses and other malware onto your computer via the browser extension.

Security software like antivirus programs tries to keep an eye on extensions, but can't catch 100% of the problems.

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When are They Good and When are They Bad?

A browser extension is good if it adds useful functionality and doesn't impact the performance or stability of the browser.

But an extension is bad if it slows down (or crashes) your browser. It's also bad if it does things without your knowledge like collecting your browser behavior or installing malware.

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Known BAD Extensions

This is not a complete list, but the following extensions have been flagged by security researchers as problematic and should be removed (see section below for details):

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Your Best Defense

  Do research before installing an extension. Make sure it has a large number of high star ratings and a lot of good reviews. But also read the average score reviews to learn about potential problems. An extension with recent updates is generally safer than one that hasn't been updated in a while. Run a Google search on “[extension name] reviews” to see what several different sites say about it.

  Keep the number of extensions installed in your browser as low as possible. The more you have, the more likely one of them is dangerous or they slow your browser down.

  If possible, try to use extensions built directly by the browser makers (Google for Chrome, Mozilla for Firefox, Apple for Safari, and Microsoft for Edge)

  Uninstall any extensions you do not actively use or don't remember installing. (Some malware will install extensions when you're not looking.) How to uninstall an extension depends on the browser you're using — see below.

(Note that these links will open in a new tab or window and that you may have to scroll down to see the removal instructions.)

  Google Chrome

  Mozilla Firefox

  Apple Safari

  Microsoft Edge

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Some Good Browser Extensions

There are some safe and helpful extensions. See our free resources page for details.

Adblock Plus

Avast Online Security

HTTPS Everywhere

Disconnect.me

Privacy Badger

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Summary

When browser extensions are safe to use, they can add a lot of value to your web browser and provide useful functionality. Use the advice above to be sure your extensions are working for you and not against you.

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Questions?

If you have any questions about anything here or if there's an issue you'd like us to write about please get in touch.