Adware - Unwanted Ads and Hidden Tracking Risks

About 2 min read

Adware is software that forcibly displays advertisements against the user's intent. It is often installed bundled with free software, displaying pop-up ads in the browser, tampering with search results, or changing the home page without permission. Beyond being merely a nuisance, in many cases it also has spyware functionality that collects the user's browsing history. Between 2024 and 2025, cases of legitimate browser extensions turning into adware after being acquired have increased, and several extensions have also been removed from the Chrome Web Store.

What a Flood of Pop-Up Ads Tells You

When a browser suddenly starts displaying a large number of pop-up ads, adware bundled with the installation of free software is one of the likely causes. Adware of this kind does not necessarily stop at showing ads: it may also send browsing history to an external destination, which makes it a data-leak problem rather than merely an annoyance.

How Adware Spreads and Behaves

If you proceed with the default settings instead of choosing "custom installation" when installing free software, adware may be installed at the same time. Cases of intrusion via browser extensions are also increasing, and there have been reports of legitimate extensions being acquired and turned into adware. Once infected, ads that do not originally exist are inserted into web pages, and clicks are redirected to ad networks.

The Difference from Spyware

The main purpose of adware is to earn advertising revenue, centered on displaying ads to the user. Spyware, on the other hand, aims to covertly collect and transmit the user's personal information, passwords, credit card details, and the like. However, the boundary between the two is blurry: adware that collects browsing history and uses it for ad targeting also has the characteristics of spyware. You can reduce both risks by optimizing your privacy settings.

Countermeasures and Prevention

When installing software, always choose custom installation and uncheck any unnecessary bundled software. Use only browser extensions from trustworthy developers, and periodically remove extensions you no longer need. Protect your browser sync account with a strong random password to prevent the installation of unauthorized extensions. Regular scans with anti-malware software are also effective.