Browser extensions — also known as browser add-ons — have become an integral part of our everyday web browsing experience. From ad blockers and password managers to translation tools and productivity plugins, they promise convenience, speed, and functionality. However, behind that convenience lies a growing threat: malicious extensions.
What are browser extensions?
Extensions are small applications that are installed on Chrome, Firefox, Edge or any other modern browser and extend its capabilities. They are integrated directly into the browser and can manage various functions: from configuring the appearance of web pages to storing data or communicating with external services.
See also: Mozilla Firefox: New system blocks extensions that steal crypto
The dangers of malicious browser extensions
Like any software, extensions can be used for malicious purposes. Many times, the problem is not so obvious: a seemingly useful extension can contain spyware, adware, and even keyloggers.
The most common risks include:
- Data Snooping: Extensions can read page contents, record keystrokes (such as passwords), and track your every move online.
- Displaying ads (malvertising): Through malicious scripts, they insert ads or even phishing content into regular pages.
- Access to sensitive accounts: Some browser extensions ask for permission to read and change data on all pages you visit, even banks or email clients.
- Backdoor attacks: Sometimes, extensions are purchased by malicious actors and silently updated with malicious code after months of innocent operation.
See also: Chrome: Over 100 malicious extensions detected
How to protect yourself
The good news is that there are practical ways to protect yourself from malicious extensions, without stopping using them entirely. Here are the most effective measures:
1. Download extensions only from official stores
Stick exclusively to the Chrome Web Store, Firefox Add-ons , and Microsoft Edge Add-ons Store. While they aren't completely secure, they have vetting processes and can remove problematic extensions.
2. Check permissions carefully
Before installing an extension, look carefully at what it asks for. If a “dark mode” plugin requires access to all your data and tabs, it’s a sign of poor design or malicious intent.
3. Read reviews and number of users
The absence of ratings or the presence of identical reviews is a frequent sign of a malicious extension.
4. Update and monitor your extensions
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Periodically check which extensions you have installed, and disable/remove those you don't use. Old extensions with zero support are easy targets for hijacking by third parties.
5. Use security extensions and antivirus
Some plugins provide additional protection against malicious scripts, while some antiviruses can detect malicious extensions before they are activated.
6. Avoid “broken” extensions from unofficial sources
Extensions that you download as .crx or .xpi from random forums or sites are a big risk. There is no way to check what they do, especially if they contain obfuscated code.
See also: Research: Many browser extensions pose a risk to businesses
The balance between usability and security
Browser extensions are great tools, but they require caution. Just as we wouldn't let a stranger manage our house keys, we shouldn't allow unknown software to have full access to our browser — which is often the "gateway" to our online lives.
The best protection is awareness, periodic inspection of installed tools, and a healthy dose of distrust.
