Why security extensions can worsen your privacy

¿Why using security extensions can worsen your privacy? Browser extensions have become so commonplace that we often install them almost without thinking. Block ads, save time, automate tasks, improve security or privacy…in theory they sound wonderful. But behind that innocent-looking icon in your browser bar, a serious problem can be lurking for your data, your online accounts, and even your company's network.

The paradox is that some of the tools that promise to protect your security or anonymity can actually do just the opposite. VPN extensions, tracker blockers, password managers, or “security” add-ons They can end up collecting your browsing history, reading everything you type, or opening the door to malware and fraud. Let's see why this happens, what real risks exist, and what you can do to minimize the damage without completely abandoning extensions.

What exactly are hair extensions and why have they become essential?

An extension or add-on is, essentially, a small program that runs inside the browser (Chrome, Firefox, Edge, Safari, Opera, etc.) and adds new features. They can change the interface, intercept and modify page content, communicate with external services, or integrate with other applications you use daily.

Thanks to these pieces of software we can block ads and pop-ups, translate websites on the fly, save notes, manage passwords, force the use of HTTPS, take screenshots, or automate repetitive tasksWe used to do many of these things by installing entire programs on the system; now we solve it with two clicks in the extensions store.

Modern browsers like Chrome, Chromium, Firefox, Safari, Opera, Edge or even Internet Explorer at the time They allow you to install a huge number of add-ons. There are thousands dedicated to productivity, shopping, gaming, customization, SEO, accessibility, office applications, and, of course, security and privacy.

In corporate environments, extensions have also become popular as a quick way to add functionality without significantly altering the systems. When company policies prevent the installation of full programs, many employees resort to extensions to "fix" what they need.from screen capture tools to AI tools or file downloads.

The problem is that this ease of installation clashes head-on with the technical reality: in order to function, many extensions need deep access to your browser, the pages you visit, and even your credentials and cookiesRight in the most sensitive area of ​​your digital life.

Why extensions can pose a serious privacy risk

To do its job, an extension usually requests elevated permissions: Read and modify the content of all the websites you visit, access your tabs, capture your history, manage cookies, use the clipboard, microphone, or camera, and even interact with external applications or your file system.

In Chrome and other browsers, these permissions are displayed during installation, but the reality is that If you don't accept them, the extension simply won't work.And since most users just want the promised functionality, they end up accepting it without stopping to think if that level of access makes sense.

This puts extensions in a privileged position: They can see almost everything you do in your browserIf a plugin wants to record what you type, read your webmails, capture your banking sessions, or analyze your entire history, it's technically very easy for it if you've given it those permissions.

It doesn't help that antivirus and other traditional security solutions They don't always detect malicious behavior in extensions. Many of them are distributed through official stores like the Chrome Web Store or Firefox Add-ons, where they undergo preliminary checks, but these filters aren't infallible and, sometimes, malicious add-ons slip through or become malicious later on.

In the case of “security” extensions (VPNs, tracking blockers, password managers, anti-phishing tools, etc.), the privacy risk multiplies, because We entrust them with precisely the most sensitive part of navigationA design flaw, an aggressive data policy, or a change of ownership can completely change the behavior of something you installed thinking it was protecting you.

Common security and privacy risks when using extensions

Studies on large volumes of extensions (hundreds of thousands have been analyzed in corporate environments) agree on something quite worrying: a very high proportion presents significant risksWe're going to break down the most important ones and how they manifest themselves in everyday life.

Excessive permissions and abuse of privileges

One of the most common problems is that of extensions that ask for much more than they need for the function they promiseFor example, a simple notepad in your browser that requests access to all your data on every website, or a color-changing extension that wants to read and modify the content of any page you open.

With that level of permission, an extension can monitor your behavior, profile you, collect form data, intercept credentials, or spy on your conversationsIn a personal setting it is already serious; in a company it can mean exposing financial information, internal communications or intellectual property to unknown third parties.

Malicious code injection into web pages

Many extensions work by injecting code (scripts) into the pages you visit to alter the content or add buttons and functions. The problem arises when this ability is used to inject malicious code that steals passwords, hijacks sessions, modifies forms, or redirects to phishing websites without you realizing it.

These types of attacks, often called man-in-the-browserThey can bypass traditional controls because, from the system's perspective, everything appears to be legitimate browser traffic. In a company, this type of injection can be used to move laterally through the network, steal data from internal applications, or open backdoors that are very difficult to trace.

Silent data exfiltration and invasion of privacy

Another sadly common practice is the massive collection of browsing history, searches, visited URLs, form data, or even session tokenswhich are then sent to third-party servers. Sometimes this is done for clearly malicious purposes, and other times as a “legitimate” business model, selling this (supposedly anonymized) data to advertising or analytics companies.

The problem is that this data is rarely completely anonymous. With enough information, it's very easy to re-identify people and to know what pages they visit, what they buy, what they work on, or what services they use. There are notorious cases, such as the Web of Trust extension, which collected the complete browsing history of its users and ended up being removed from several stores for selling insufficiently anonymized data, and there are also incidents of massive data breaches like the one in massive Instagram leak which show the extent of these leaks.

Regulatory compliance risks and penalties

In the business world, data exfiltration through extensions can directly clash with regulations such as GDPR, CCPA, PCI-DSS or other data protection lawsIf a plugin collects or filters personal or financial information without a legal basis, the responsible party is not the developer: it is the organization that allows that processing from its equipment.

This can lead to significant fines, class action lawsuits, and reputational damageFurthermore, these incidents often leave no trace on network monitoring systems because the communication exits as legitimate HTTPS traffic from the browser to seemingly normal domains.

Attacks on the extensions supply chain

An increasingly common attack vector is that of purchase or hijacking of legitimate, already established extensionsThe pattern is usually the same: a reputable extension with many users is sold to another company, or the developer's account is compromised. The new owner releases an update that introduces malicious code, adware, or aggressive tracking mechanisms.

Since extensions are updated automatically, Millions of users can go from having a harmless tool to spyware without realizing itCases like Copyfish or Particle illustrate this risk very well: well-known extensions that, after a change of control, became vehicles for intrusive ads or dubious tracking practices.

Credential theft, session hijacking, and keylogging

When an extension has access to all the pages you visit, it also has access to Forms where you enter passwords, bank card fields, session cookies, and tokens that identify you on online servicesYou don't need to "hack" HTTPS encryption; you see it directly in the browser.

With that access, a malicious add-on can intercept your credentials, capture keystrokes (keylogging), copy session cookies to impersonate you or manipulate login pages to steal data. This affects both personal accounts (email, banking, social media) and internal company access (VPN, administrative panels, CRM, etc.).

Resource hijacking and cryptocurrency mining

Another common use of malicious extensions is to exploit your computer's processing power to mine cryptocurrencies or integrate it into a botnetYou might only notice that the computer is running slower, the fan is constantly running, or the battery is draining quickly, but behind the scenes your CPU is working to fund the attacker.

In addition to the cost in performance and energy, this type of abuse can degrade corporate services, affect servers, or cause widespread performance drops if it spreads across many devices on the network.

Operational impact on organizations

In a company, a single problematic extension installed by an employee can trigger security incidents that require mobilizing the IT team, conducting forensic analysis, informing clients or regulators, and reviewing internal policies, as could be seen in the cyberattack on EndesaAll of that involves time, money, and distractions from the core business.

Paradoxically, many extensions are installed precisely to "improve productivity." But if those same tools cause disruptions, regulatory sanctions, loss of customer trust, or data breachesthe final balance can be very negative.

“Security” extensions that can worsen your privacy

Within this entire ecosystem, that group of extensions that are sold as deserves special mention. security, privacy or protection solutionsLightweight VPNs for the browser, tracking blockers, password managers, website reputation checkers, "safe browsing" and much more.

These tools, by design, need to see much more than a normal extension: They manage your traffic, your passwords, your authentication tokens, or your most sensitive URLsThis means that if their business model relies on data collection, or if their data ends up being compromised, the potential damage is greater than with a simple banner blocker.

There are several typical problem scenarios:

• free browser VPNs that record the traffic passing through them and monetize it by selling usage data.
• Privacy extensions that promise to block trackers but, in return, insert their own identifiers and analytics.
• Website reputation tools that send all the URLs you visit to external servers to "evaluate" them.
• Corporate security add-ons which, if not properly audited, can become a single point of failure for data and identities.

Even when these extensions are not malicious in themselves, their monetization method often involves the intensive collection of supposedly anonymous browsing dataBut as we have already seen, anonymization is fragile and any leak or sale to unscrupulous third parties can end up exposing the online behavior of thousands or millions of users.

That's why it's especially important Read in detail the privacy policy, permissions, and reputation of extensions that claim to protect youThe mere fact that they are called “Security”, “Privacy”, “Safe” or similar does not mean that they act in your favor.

How to assess if your extensions are safe (typical cases)

Many user questions revolve around specific extensions: VPNs for Chrome, dark modes like Dark Reader, add-ons to save AI chats or see YouTube dislikesCan they access your passwords? Can they read everything? The short answer is: it depends on their permissions and how they are programmed.

In general, an extension with access to “read and modify all your data on the websites you visit” could, in theory, intercept login forms, capture text, view cookies, and access virtually anything that passes through the browserThis includes passwords you enter (even if they are managed by the browser itself) and highly sensitive data.

However, that doesn't mean all extensions with that permission will do so. This is where they come into play. the developer's reputation, other users' opinions, the age of the extension, privacy policies, and, in the business context, security audits.

As a home user, your actual control is based on a few good practices: Only install from official stores, keep the number of extensions to a minimum, regularly review what you have installed, and be wary of newly released add-ons without reviews or with excessive permissions. for the function they claim to offer.

In companies, this shouldn't be left to the discretion of each employee: it's key Implement centralized policies that allow only a set of approved extensions, monitor their usage, and disable any suspicious or unnecessary add-ons.There are specialized security solutions that track all extensions present in the organization, score their risk, and automatically block dangerous ones.

Best practices for using extensions without compromising your privacy

Completely abandoning extensions is unrealistic, and in many cases unnecessary. The key lies in reduce the attack surface and regain some control over what you install and what you allow others to seeThese guidelines are useful both at a personal level and, when adapted, in business environments.

First of all, it's worth it limit yourself to the official browser stores (Chrome Web Store(Firefox Add-ons, Microsoft Edge Add-ons, etc.). Although not infallible, they apply much stricter security checks than third-party repositories, random websites, or links circulating on forums and social networks.

Before installing anything, take a few seconds to Check the reviews, the number of users, the date of the last update, the developer's website, and whether there are any news reports about associated security incidents.An extension with millions of users, a good track record, and active maintenance generally offers more guarantees than a newly released experiment with no reviews.

Another important step is to pay attention to permissions: If you want a simple utility for a single site (for example, Amazon or YouTube), it's preferable to choose extensions that are limited to that domain. And don't ask for access to all websites. If a specific function doesn't need to access your credentials, cookies, or browsing history, be suspicious of any additional permissions that don't seem justified.

In addition, it is advisable Periodically review the list of installed extensions and disable or remove any you don't actually use.The fewer you have, the lower the risk of a sneaky update or change of ownership affecting you without you noticing.

For tasks where an extension would need to see everything (for example, spell checkers that act on every text box), consider less invasive alternatives: Use an external website where you paste the text, use trusted desktop tools, or use separate browsers for different tasks. (one with few extensions for banking and sensitive transactions, another more "loaded" one for less critical things).

It also helps a lot Keep your browser and operating system up to date, and enable two-step authentication on your main accounts. and use a reliable security solution capable of detecting suspicious behavior in extensions (even if they were initially legitimate and have been compromised).

In organizations, these ideas translate into more formal measures: Extension approval processes, inventories of authorized add-ons, monitoring of permission changes, alerts for anomalous behavior, and tools that prevent the user from installing unverified softwareSome browser security platforms deploy themselves as extensions, but are focused on giving IT visibility and control over the rest of the ecosystem.

Ultimately, each installed extension is a piece of software that you choose to entrust with part of your digital life. The more access you give to your data, the more careful you should be in choosing and monitoring it.Used wisely, they can still be great allies; used carelessly, they become a perfect gateway to intrude on your privacy and, if you're not careful, on that of your company.