Published Jul 19, 2023
Contribute to Docs

Adware is software that displays unwanted (and sometimes irritating) pop-up adverts which can appear on a computer or mobile device. In some cases, adware can even track online behavior and display personalized ads.

Adware is short for advertising supported software, designed to throw advertisements up on the screen, most often within a web browser.

Typically, it uses an underhanded method to either disguise itself as legitimate, or piggyback on another program to trick people into installing it on their PC, tablet, or mobile device.

Signs that a PC may be infected with unwanted adware include:

  • An unexpected change in the web browser home page
  • Web pages not displaying correctly
  • Being overwhelmed with pop-up ads — sometimes even if not browsing the internet
  • Slow device performance
  • Device crashing
  • Reduced internet speeds
  • Redirected internet searches
  • Random appearance of a new toolbar or browser add-on

On a phone, signs are similar:

  • The phone is slow
  • Apps take longer to load
  • The battery drains quickly
  • The phone has apps the user doesn’t remember downloading
  • There is unexplained data usage and higher than expected phone bills
  • There are numerous ad pop-ups

Preventing Adware

In general, to be more protected against all cyber threats, including adware, implement the following best practices:

  • Keep all software updated. The most recent updates for apps, system drivers, operating system (OS), and other software have security fixes in them. Developers constantly discover vulnerabilities and patch software to protect from threats.
  • Be cautious, not curious. In the digital world, treat anything unknown or unusual as a potential risk. Hackers take advantage of everything from USB charging stations to impersonating friends on social media to infect users with adware and malware. Always ask, “what’s the worst that can happen if this is malicious,” and proceed with caution.
  • Pay attention to the details. Whether it’s a legitimate program installation or a link in an email, always pay attention to what’s being opened or accepted. Criminals try to mimic trusted URLs, email addresses, and social media profiles to catch people off guard. Taking a moment to examine these elements can reveal odd details that are red flags for scams.
  • Keep activities legal. Aside from the obvious risks, when people pirate media and software it puts them closer to seedy criminals that take advantage of their desire for “free stuff.” These services might encourage adware installs or carry infected downloads — whether they know it or not.

When downloading free computer software, mobile apps, or browsing the web:

  • Always read all terms and checkbox agreements before clicking “next” during software installation. A lot of sponsored third-party software is opt-out, meaning a box may have to be unchecked to avoid installing any accompanying PUA.
  • Only download programs from trusted, reputable sources. Try to only download from brands you recognize. Be sure that they have a trustworthy history as well. Official app stores like Google Play are not entirely free of malicious apps, but they are more likely to be safe.
  • Read reviews. Everything from browser extensions to computer programs should have reviews somewhere online. Search for user feedback and take note of the negatives.
  • Look before clicking (or tapping). Some ads rely on social engineering to take advantage of unintended clicks. Fake close buttons, carefully placed confirm buttons, and spontaneous pop-ups all get users to click an infected link. Be sure to avoid falling for it.
  • Keep an eye on bank statements. Unexpected subscription charges could be a sign of falling victim to mobile adware.

All contributors

Looking to contribute?

Learn Cybersecurity on Codecademy