What malvertising is and how it works

Malvertising is malicious advertising—ads that are designed to trick you into visiting dangerous pages, running harmful files, or handing over credentials. Unlike normal ads that point to legitimate websites, malvertising aims to create outcomes that benefit attackers: malware infection, phishing, drive-by installs, or fraudulent purchases.

A typical chain looks like this: you load a webpage, an ad impression is served, and the ad content triggers something unexpected—often a redirect to a sketchy domain, a fake “update” or “support” message, or an offer to download an installer. Some campaigns try to blend in with the look of the page (or with legitimate ad placements), which is why the “it was just an ad” assumption can be risky.

How to get rid of malvertising in practice

“Get rid of” in this context usually means reducing exposure and stopping the unwanted outcomes. You generally can’t control every ad exchange or prevent every attack, but you can make harmful delivery less likely and reduce damage when you encounter it.

Start by focusing on your browser’s trust signals and your own behavior:

  • Be cautious with ads that prompt downloads, urgent security warnings, or account “verification” steps.
  • Avoid enabling permissions that a pop-up or ad claims you need (notifications, location, or “allow” prompts).
  • Treat unexpected redirects as a warning sign, especially if the destination doesn’t match the context where you clicked.

Then harden the environment around your browsing:

  • Keep the operating system and browser updated so you benefit from fixes for known vulnerabilities.
  • Use reputable protections (browser protections, anti-malware, and safe browsing features) and ensure they are enabled.
  • Review installed extensions; remove anything you don’t recognize or don’t need, since extensions can increase risk or interfere with security checks.

Finally, reduce the “blast radius” if something does slip through:

  • Use strong, unique passwords and enable multi-factor authentication (MFA) for important accounts.
  • Separate high-value activities (email, banking, account management) from general browsing where feasible.

Key differences: malvertising vs. phishing, scams, and drive-by downloads

Malvertising overlaps with other threats, but the primary “entry mechanism” differs.

  • Malvertising: the malicious component is delivered via advertising (impression/click-driven). The ad itself—or what it redirects to—creates the threat.
  • Phishing: the core goal is to obtain information (passwords, one-time codes) through impersonation or social engineering. Ads can lead to phishing pages, but phishing is about the trick used to collect secrets.
  • Scams: the goal is usually money or personal data through manipulation (fake prizes, tech support offers, counterfeit storefronts). Malvertising can be part of a scam funnel.
  • Drive-by downloads: malicious files are obtained without the user intentionally downloading them from a clear, trustworthy source. Malvertising can trigger drive-by behavior through redirects or exploit chains.

A practical way to place what you’re seeing is to ask: “What was the first suspicious moment?” If the first wrong moment was an ad click or ad-triggered redirect, you’re likely dealing with malvertising. If the first wrong moment was a login prompt for “verification,” you’re likely dealing with phishing, regardless of how you arrived.

Differences and limits: what you can and can’t fix

It’s important to recognize limitations so you don’t chase the wrong target.

First, malvertising is dynamic. Attackers can change redirects, domains, and landing pages quickly. That means static “block once and you’re done” approaches may not keep up indefinitely.

Second, ad ecosystems are complex. Even with good browser protections, some malicious deliveries can still slip through, especially if they only trigger under certain conditions (device type, location, or timing). Your defenses should therefore be layered rather than single-point.

Third, removing one vector doesn’t stop all risk. If you keep installing untrusted extensions, ignore system prompts, or reuse passwords, attackers still have other ways to succeed—even if a particular malvertising campaign ends.

In short: you can’t reliably guarantee zero exposure, but you can substantially reduce the probability of infection and the impact of successful attempts by combining updated software, safer browsing behavior, and strong account security.

Practical checks after you suspect a malicious ad

If you think you encountered malvertising, use checks that confirm what happened rather than guessing.

  1. Check the URL path and destination history Look at where the redirect actually took you (not just what the ad looked like). Confirm whether the domain changed unexpectedly, whether the path looked suspicious, or whether the page asked for downloads you didn’t initiate.

  2. Inspect downloads and recently installed changes Review your browser’s downloads list and your system’s recent activity. If a file was downloaded, note where it came from and whether it prompted you to run something.

  3. Verify account signs-in If you entered credentials, check your email and account security pages for recent sign-ins. Treat any unfamiliar activity as a sign you should reset credentials and secure sessions.

  4. Run a security scan Use your anti-malware tooling to scan the device. If you find suspicious software, follow your security tool’s remediation steps rather than trying to “guess” what to remove.

  5. Reduce recurrence signals Remove risky or unknown extensions, and consider whether a certain site regularly leads to suspicious redirects. While this may not eliminate all malvertising, it helps you focus on repeat patterns.

If something “doesn’t add up”—for example, a page claims to be an official security feature but asks you to download an installer—stop and re-check before proceeding.