Are Browser Extensions Spying on You? Safety Guide

You just installed a browser extension that promised to block ads or help you find coupons. It has thousands of five-star reviews and millions of downloads. It must be safe, right?

Not necessarily. In 2025 alone, malicious browser extensions affected over 2.3 million people. One popular cryptocurrency wallet extension was hacked, leading to $7 million in stolen funds. Extensions with perfect ratings and Featured badges from Google turned out to be stealing passwords, recording conversations with AI chatbots, and hijacking bank accounts.

If you use Chrome, Firefox, Edge, or Safari, you need to understand this threat. But don't panic. You can protect yourself with a few simple steps that take less time than your morning coffee.

What's Actually Happening

Browser extensions are small programs that add features to your web browser. They can block annoying ads, manage passwords, translate web pages, or change how websites look. Most people have at least a few installed. Many have a dozen or more.

Here's the problem: these extensions have extraordinary access to everything you do online. A malicious extension can record every password you type, steal the cookies that keep you logged into websites, take screenshots of your banking activity, and track every website you visit. It can inject fake login forms into real websites, redirect you to phishing sites, and send all this stolen data to criminals.

The threat is real and growing. Security researchers discovered that even extensions with millions of users and years of clean operation can suddenly turn malicious. WeTab, a productivity extension with three million users, operated perfectly for years before a single update transformed it into spyware. Trust Wallet, a legitimate cryptocurrency extension, was compromised when hackers broke into the developer's account and pushed a malicious update to hundreds of thousands of users.

Perhaps most concerning is the new practice called "prompt poaching." Malicious extensions now eavesdrop on your conversations with ChatGPT, Claude, and other AI chatbots. Urban VPN Proxy, with six million installations and a 4.7-star rating, was caught harvesting complete AI conversation transcripts. If you've shared work documents, source code, or personal information with an AI tool, that extension grabbed everything and sent it to attacker-controlled servers.

How They Steal Your Data

Understanding how these attacks work helps you protect yourself. Malicious extensions use several methods to steal your information.

Keylogging is straightforward but devastating. The extension records every keystroke you make, capturing usernames, passwords, credit card numbers, and anything else you type into websites. This data gets packaged up and sent to the criminals' servers, often in real-time.

Cookie theft is more subtle but equally dangerous. When you log into a website, it stores a cookie in your browser that keeps you logged in. Malicious extensions steal these cookies, allowing hackers to access your accounts without needing your password. You remain logged in and might not notice anything wrong while someone else is simultaneously accessing your email, bank account, or social media.

Page injection involves the extension modifying legitimate websites you visit. It might add an invisible form that captures information you enter, create a fake login page that looks identical to the real one, or alter banking websites to steal transaction details. Because these changes happen inside your browser, security certificates and website URLs appear completely normal.

Traffic hijacking routes your internet activity through servers controlled by criminals. They can see everything you do online, modify web pages before you see them, redirect you to phishing sites, and inject malicious content into legitimate pages. The Phantom Shuttle extensions, active since at least 2017, used this method to target over 170 high-value domains including developer platforms, cloud services, and social media sites.

These aren't theoretical attacks. They're happening right now to real people. The only question is whether you're prepared.

How Bad Extensions Get on Your Computer

You might think downloading from the official Chrome Web Store or Edge Add-ons protects you. It doesn't. Malicious extensions regularly appear in these stores, often with impressive trust signals that make them look legitimate.

They have thousands of five-star reviews. Many of these are fake, posted in huge batches by bot accounts or paid reviewers. The reviews say generic things like "Great extension!" or "Works perfectly!" without any detail about what the extension actually does.

They show Featured or Verified badges from Google and Microsoft. These badges indicate the extension passed an initial review, but that review is a one-time check. Once approved, extensions can push updates without additional scrutiny. Attackers exploit this by keeping extensions clean during review, then weaponizing them later.

The "long con" strategy demonstrates sophisticated patience. Criminals create or purchase legitimate extensions, operate them normally for years, build up millions of users, and then flip a switch with a malicious update. WeTab operated cleanly for years before turning malicious in 2024. Users had no reason to suspect anything was wrong until it was too late.

Brand impersonation creates confusion by design. Attackers create fake extensions with names like "ChatGPT for Chrome," "Free VPN Pro," or "AdBlock Plus Extra" that look almost identical to legitimate tools. The names are similar enough that users don't notice the difference. The icons match. The descriptions sound right. But they're completely different extensions controlled by criminals.

Supply chain attacks target the developers themselves. Instead of creating a new malicious extension, attackers compromise a legitimate one. They might phish the developer's login credentials, exploit weak account security, or use OAuth vulnerabilities to gain access to the developer's Chrome Web Store account. Once inside, they push a malicious update to the real extension. This is what happened to Trust Wallet, where a compromised developer account led to $7 million in stolen cryptocurrency.

Red Flags You Need to Know

Before you install any extension, look for warning signs. Check the developer information. Legitimate companies have real websites with contact information. If the developer only lists a Gmail or Hotmail address, that's suspicious. If you can't find any information about the company online, don't install it.

Read the permissions carefully. Extensions request access to specific browser capabilities, and you should read this list before clicking "Add." Does the extension request permissions that match what it claims to do? A calculator has no business reading your browsing history. A weather extension doesn't need access to your cookies. A wallpaper changer shouldn't require permission to modify website content.

Pay special attention to permissions that say "read and change all your data on websites you visit." This gives the extension complete access to everything you do online. Some extensions legitimately need this access, but many don't. If you can't explain why an extension needs a particular permission, don't grant it.

Look at the reviews critically. All five-star reviews with generic comments suggest manipulation. Check when reviews were posted. If thousands appeared on the same dates, they're probably fake. Read the negative reviews carefully. Users who experienced problems often leave detailed warnings about data theft or suspicious behavior.

Check the extension's age and update history. Brand new extensions with thousands of reviews arrived at that number too quickly. Legitimate extensions build user bases gradually. Also check when it was last updated. Extensions that haven't been updated in six months or more might be abandoned, which creates security vulnerabilities even if the developer had good intentions.

After installation, watch for warning signs that something's wrong. Suddenly seeing ads on websites that normally don't have them indicates ad injection. If your homepage or search engine changed without you doing it, that's browser hijacking. Slower browser performance, unexpected logouts from accounts, friends reporting spam from your accounts, or new toolbars appearing all signal potential problems.

How to Protect Yourself

Protection starts before you click the install button. Ask yourself if you really need the extension. Can your browser already do this without an add-on? Is there a safer alternative? Are you installing this because you need it, or because an advertisement told you to?

Spend two minutes researching. Google the extension name followed by "scam" or "safe" and read what appears. Check when it was published. Look at the developer's other extensions. Read the negative reviews. This brief research catches most malicious extensions before they reach your browser.

Review your current extensions today. Open your extensions page by typing chrome://extensions in Chrome, about:addons in Firefox, or edge://extensions in Edge. Look at each extension and ask: Do I use this regularly? Do I even remember installing this? Has it been updated recently? Remove anything you don't recognize, haven't used in a month, or can't remember installing.

Make this a monthly habit. Set a calendar reminder to review your extensions once a month. Remove ones you're not using. Check if remaining ones still receive updates. Keep your total under five to seven extensions. Fewer extensions means less risk.

If you suspect an infected extension, act immediately. Go to your extensions page, find the suspicious one, and turn it off. If your problems stop, you've found the culprit. Click Remove to uninstall it completely. Then clear your browsing history, cookies, and cached data to remove any tracking mechanisms the extension left behind.

Secure your accounts after removal. Change passwords for important accounts, especially banking, email, and social media. Turn on two-factor authentication everywhere it's available. Check your bank statements for unauthorized charges. Log out of all devices in your account settings and log back in with your new password.

What About "Safe" Extensions?

People often ask which extensions they can trust. The honest answer is that no extension is 100% safe. Even good extensions can be hacked, sold to malicious buyers, or compromised through developer account breaches. The safest approach is using as few extensions as possible.

That said, some extensions from established sources are generally safer bets. Password managers like 1Password, Bitwarden, or your browser's built-in manager serve important security functions. Ad blockers from reputable sources like uBlock Origin (not "uBlock," which is different) or Privacy Badger from the Electronic Frontier Foundation have good track records. Security-focused extensions like HTTPS Everywhere from established nonprofit organizations tend to be safer choices.

But here's the catch: even trusted extensions have been compromised. Trust Wallet was legitimate before the hack. WeTab was safe for years before turning malicious. Your vigilance can't stop when you install an extension from a trusted source. Stay alert, review regularly, and remove anything that shows warning signs.

Your Safety Checklist

Let's make this practical. Here's what you should do right now:

Open your browser's extensions page and count how many you have. Remove any you don't recognize. Remove any you haven't used in a month. Check that remaining extensions were updated within the past six months. Enable two-factor authentication on your important accounts. Set a monthly calendar reminder to review your extensions again.

Follow these simple rules going forward. Only install from official browser stores. Never download extension files from random websites. Research before installing. If you can accomplish a task without an extension, do that instead. Keep under five to seven total extensions. Remove anything you don't use weekly. Update your browser automatically.

For banking and sensitive activities, use a separate browser with zero extensions. Never install extensions claiming to enhance banking features. Don't access bank accounts on public WiFi. Consider using your bank's mobile app instead of the browser.

You're Now Safer Than Most People

You just learned more about browser extension security than 95% of internet users. That knowledge makes you safer. Criminals rely on people not knowing this information. Now you know.

Browser extensions can be dangerous. Millions of people have been affected. The threat is real and growing. But you don't need to be paranoid. Stay alert, not anxious. Be picky about what you install. Review regularly. Remove aggressively. Use as few extensions as possible.

That extension promising to make your life easier might actually make it much more complicated. When in doubt, leave it out. Your digital safety is worth more than any convenience a browser extension might provide.

Take 15 minutes today to clean up your extensions. Your future self will thank you.