The hidden dangers of browser extensions – and tips on how to keep away from them

Not all browser add-ons are useful helpers – some might include excess of you could have bargained for

29 Jul 2025
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4 min. learn

What would we do with out the net browser? For many of us, it’s our gateway to the digital world. However browsers are such a well-recognized instrument at present that we’re at risk of giving them a free trip. In reality, there are many rogue extensions masquerading as respectable advert blockers, AI assistants, and even safety instruments which are designed to steal our knowledge, ship us to malicious websites and flood our display screen with popups. For instance, earlier this yr, a malicious marketing campaign was uncovered that will have impacted dozens of extensions and compromised practically three million customers.

Subsequent time you’re fascinated by downloading an online browser add-on, assume by way of the next dangers.

Why extensions matter

Browser extensions are an more and more well-liked automobile for menace actors. They offer attackers entry to an enormous quantity of delicate data, with folks typically trusting these add-ons, particularly in the event that they’re downloaded from official sources. Additionally, extensions present a number of avenues for monetization and malicious exercise and usually give assaults a greater probability of success and are a menace additionally in company settings, the place they could typically keep beneath the radars of safety groups and instruments.

Nonetheless, by putting in and granting an extension permissions, you might unwittingly be enabling malicious actors to entry your most delicate knowledge – all the things from looking historical past to saved logins and session cookies, which may very well be abused to hijack your accounts.

When browsers go unhealthy

A 2023 danger evaluation of 300,000 browser extensions and third-party OAuth purposes utilized in company environments revealed that half (51%) of the previous had been excessive danger and will probably have brought on “in depth harm.”

So how may they find yourself in your machine? Malware could also be hidden in legitimate-looking browser extensions like these purporting to be advert blockers or PDF converters and even safety enhancements. They may very well be packaged up and positioned on browser shops for unwitting customers to obtain, bundled with different software program, shared by way of misleading hyperlinks or uploaded to platforms outdoors your official internet retailer, the place hackers depend on customers “sideloading” with a view to goal them.

Sideloading is especially harmful as a result of third-party shops don’t function the sort of safety critiques and different checks that official marketplaces have in place. Meaning they’re extra prone to function dangerous add ons spoofed to look as if respectable.

Alternatively, menace actors may hijack or purchase a respectable extension and use it to ship malicious updates to its total person base. Typically, extensions can appear respectable, however on activation shall be programmed to put in new payloads with malicious capabilities.

What can malicious extensions do?

The nefarious actions run the gamut and embody:

• Stealing knowledge, together with usernames and passwords, looking historical past, session cookies (which can be utilized to entry your accounts with no need a password) and monetary data. This can be sourced out of your clipboard, browser or obtained by way of keylogging as you sort it in. The tip purpose is normally to both promote that knowledge on the darkish internet, or use it on to hijack accounts and commit id fraud.
• Directing you to malicious or dangerous web sites that will harbor malware together with infostealers and banking Trojans. Different websites could also be spoofed to look as if a respectable model, however are literally designed to reap your private and monetary data and/or logins.
• Injecting undesirable adverts and attainable malware into your looking expertise. Advertisements may very well be monetized by menace actors, whereas malware could also be designed to steal credentials or harvest different profitable private knowledge for id fraud.
• Backdooring your browser in order that they’ll entry your machine at any time sooner or later.
• Mining for cryptocurrency with out your information, one thing that may decelerate and even put on out your machine fully.

Staying protected

To mitigate these dangers, warning is at all times suggested if you’re on the hunt for a brand new extension. To begin with, stick with respectable internet shops and carefully scrutinize any new add-on. Which may embody checking the developer’s credentials, studying critiques of the product and looking out individually for it to see if it has been linked to any suspicious or malicious habits up to now. Look carefully too at its permissions. If it requests any that appear to transcend what is required for the product, it ought to be a pink flag. As is the case with, for instance, cellular apps, not many extensions ought to want entry to your passwords or looking knowledge.

Extra tricks to hold your self protected embody:

• Hold your browser up to date so it’s on the newest, safer model always. This implies it will likely be higher protected in opposition to potential malware.
• Swap on multi-factor authentication on all of your on-line accounts – that may go a great distance towards protecting you protected even when a malicious browser extension does steal your passwords.
• To make your internet looking expertise safer basically, think about using a secured browser mode that’s provided along with different security-enhancing options by some safety distributors. This mode is available in notably useful if you carry out monetary and crypto transactions in your browser.
• Enhanced Protected Searching in some widespread internet browsers also can enable you avoid malicious websites.
• Importantly, use safety software program from a good vendor, and carry out periodic scans to test for something suspicious working in your pc. It should go a great distance in direction of stopping you downloading malware from third-party websites, or redirecting to a phishing website.

Each piece of software program we set up, irrespective of how small, comes with a component of belief; certainly, this belief could also be notably vital with browser extensions, as they function straight inside your gateway to the web. Think twice in regards to the worth or comfort that an extension supplies versus the potential danger. In the end, the purpose is to make knowledgeable selections in regards to the add-ons you permit into your digital area. make sure to supply your browser extensions and, certainly, all different software program from dependable suppliers.