What Is Malvertising

By Jayden Andrews. June 18, 2020

Cybercriminals have gotten creative over the years and came up with more ways to hack systems and networks. Some use malicious phishing emails and infected ads, and others apply malvertising. If you display some ads on your site, then you can’t ignore malvertising. Why? This practice can affect both you and your visitors as hackers force malicious content on your site without you even noticing.

What is malvertising and how it works

An example of a similar attack is the MSN Malvertising scandal that has made many people to even refrain from using the platform lately. This article shares everything you need to know about malvertising, how it works, and even ways to avoid it.

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Malvertising Definition

Malvertising is a popular and very dangerous practice used by cybercriminals to spread malware. So, what happens is attackers hack your ad network and use your site to display their malicious advertisements to users.

Hackers can also launch these attacks through advertising networks. Doing this makes it easy to distribute their malicious advertisements since these networks can’t review every ad to prove its safety.

nytimes.com malvertising


Cybercriminals usually use their ads to trick your website visitors into installing some malicious software on their devices. Mostly, they apply these two techniques:

  • Pre-click: In this technique, the malvertising campaign uses special coding or script to download the virus on your device as the ad loads. Therefore, you don’t even have to click on anything to be infected. Visiting the site with such an ad is enough to expose you to these attacks.
  • Post click- As the name suggests, malvertisement attacks you after clicking on a malicious link, ad, image, page, or ad.

Malware Vs. Adware

A lot of people confuse malvertising with adware. Adware refers to a program that runs on your computer, and it usually hides inside a legitimate software you downloaded online. Also, adware can be installed on your device without your knowledge.

adware example

Adware focuses on redirecting you to malicious sites then mines your data to understand how to trick you into clicking ads. Here are the major differences between the two that you should be aware of:

  • Malvertising only affects you if you visit an infected site while adware runs on your device continually, thus affecting you 24/7.
  • Malvertising mostly involves deploying unique malicious code on a website to affect the users. Adware, on the other hand, targets users individually.

How Does Malvertising Work?

Malvertising is made possible by the existing loopholes in the complicated system of online ad networks. Let’s look at how it works and where things usually go wrong. In malvertising, these three parties are always involved:

  • The site owner who wants to make some cash by displaying ads.
  • Advertisers who want their ads to reach the audience.
  • An online ad network that provides a significant platform to website owners and advertisers.


How does malvertising work?

1. The Website Owner

Also known as the publisher, the site owner signs up to an advertising network and submits ads for review. Most ad networks have some rules and eligibility criteria that your site must meet to receive ads. Once approved, you can now create ad space on your website to start displaying ads. Your ad space is then sold to advertisers by the ad network to start sending their ads to your page.

2. The Advertiser

Advertisers also have to sign up to the advertising network and submit their ads for approval. The advertisers can then bid for ad space on sites like yours after their ads are approved. If the bid succeeds, then an advertiser can start displaying ads on your page.

3. An Online Ad Network

Online ad networks usually have millions of customers, both publishers, and advertisers. So, they definitely receive lots of ads to approve. Although these networks have review processes to help verify ads, they can’t be thorough enough due to the huge volume. This creates a loophole that hackers take advantage of as it allows their ads to go through the review process undetected.

How Malvertising Affects Website Users

Website visitors are sometimes the most affected party as they are more likely to click on infected ads hence downloading malware on their devices. Here are some things that your site users might experience if the site is a malvertising victim:

  • The ads displayed on your site by cybercriminals will undoubtedly be about illicit content like illegal drugs, adult websites, and fake products. The content can affect users negatively, especially kids who shouldn’t be viewing such.
  • As discussed before, some malvertising campaigns might also contain a drive-by download. What this means is your website visitors will be getting forced software downloads on their devices. Hackers can then use such downloaded software to steal the user’s payment information, personal data, install ransomware, among many other malicious actions.
  • By clicking malicious ads on your website, the user can also be redirected to pages filled with adult content or phishing attacks. Such sites might conduct some social engineering attacks and steal the user’s personal information then use it to access financial accounts.

How Website Users Can Stay Safe from Malvertising

1. Use ad blockers as they keep away both ads and their malicious elements.

2. Install a great antivirus to keep you safe from drive-by downloads as it alerts you anytime a malicious element tries entering your computer.

3. Avoid using Java and Flash as they’re very vulnerable to malvertising.

4. Updating your plugins and browsers will also help to stay safe from pre-click malvertising.

5. Use an excellent VPN. Doing this helps you browse anonymously. This way, you can mask your location and keep hackers off your network.

How Malvertising Affects Publishers

Since the malvertisements are running on your website, you also have some consequences to suffer. The most common ones are:

1. As the malvertisements and unwanted content keeps spreading through your site, your reputation continues getting ruined. Experiencing regular attacks would make visitors avoid interacting with your site ever again. That way, you lose visitors, making it almost impossible to earn from ads.

2. Malvertisements use up a lot of your server resources. Doing this makes your website extremely slow, thus affecting overall performance.

3. If these ads keep redirecting users to malicious sites, then the bounce rate will increase dramatically, thus reducing traffic. The reduced traffic will have permanent effects on your website’s SEO.

4. You can also be blacklisted if Google detects the malvertisements on your site. So, users will always get a warning when trying to access your site, which also increases the bounce rate.

Fixing Malvertising Attacks

Most publishers are searching for solutions to help identify and remove malvertisement from their sites. Experts advise that you use a reliable and legit ad server. Most ad servers today have an in-built scanner that helps you identify any malicious ads on your website. Google Ad Manager is among the best ad servers that you can use. Once the Ad Manager spots malvertisements, Google suspends the responsible buyers for about three months. The platform also takes down the malicious ads hence leaving your site safe for both you and your visitors.

A reliable ad server scans malvertisements effectively hence allowing you to:

  • Get rid of the infected domains causing malvertising attacks.
  • Contact your ad network and ask them to either remove or block the creatives, enhancing the malvertisement spread.

You can use Google’s Safe Browsing Diagnostic Tool to check for malicious links on your site. Using this tool will also help you check whether any of your pages is listed as malicious, thus allowing you to remove it immediately.

How Publishers Can Avoid Malvertising

  • Scan any ad creative before displaying it to help discover malware and unwanted code.
  • Research more about ad networks to get one with an excellent review process.
  • Use a high-quality firewall to block malvertising threats from your website.
  • Ensure your site only shows specific file types such as JPG and PNG without allowing JavaScript or other codes that might expose your website to more risks

Malvertising has become a major threat to both website users and publishers all over the planet. The MSN Malvertising scandal is an excellent example that nobody is immune to malvertisements. Therefore, it’s vital that you understand malvertising properly, including its effects and ways to prevent it. This way, you’ll see the bigger picture, allowing you to be more cautious and implement an effective security strategy to avoid it.

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