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Understand and Fight Ad Fraud: A Guide for Publishers

The ad tech industry has evolved immensely over the past several years. New technologies and systems allow advertisers to take advantage of valuable ad inventory, while publishers reap the financial benefits by displaying these ads on their sites. Unfortunately, scammers and fraudsters also develop ways to exploit the system, stealing billions of dollars from advertisers and publishers. This is called ad fraud, and it’s one of the biggest challenges facing the advertising ecosystem today.

In this article, we’re going to answer questions like:

  • What is ad fraud?
  • Who is affected by fraudulent ads?
  • What are the types of ad fraud?
  • How can publishers fight against it?

Let’s begin by quickly reviewing what ad fraud is and who it affects.

What Is Ad Fraud?

Briefly explained, ad fraud is the act of defrauding ad networks to increase revenue through invalid traffic or misleading visitors with false ads. Typically, ad fraud is committed by scammers that use bots or digital trickery to steal revenue from advertisers and publishers alike.

Who Is Affected by Ad Fraud?

Everyone within the advertising ecosystem is affected by ad fraud in some way. Here’s how it affects:

  • Site Visitors: If a user clicks on a false ad, they’ll likely infect their device with viruses and malware. Often, users won’t even realize that they’ve been taken in by a scammer until they’re redirected to a different website or installed the malware.
  • Publishers: Injected ads, invalid traffic, and fake clicks can significantly lose revenue for publishers. Additionally, once ad networks and search engines identify a site as a source of fraudulent ads or traffic, they may blacklist it entirely.
  • Advertisers: Advertisers globally lost approximately $35 billion to ad fraud in 2020, and it’s predicted that the cost will rise to over $50 billion by 2025. That significantly impacts advertisers and their relationship with publishers. As advertisers become more critical of the inventory they buy, higher standards and requirements are demanded of publishers.
  • Ad networks: As ad fraud affects and effectively destroys trust between a network and publishers and advertisers, it may lose clients and revenue.

In short, no one is immune from the effects of ad fraud and losing trusted relationships and revenue to scammers.

Types of Ad Fraud

There are several types of ad fraud using different techniques and technologies to work. We’re going to describe a few of the most common types below briefly.

Pixel Stuffing

A single pixel is a tiny square part of a digital image; thousands of these pixels make up the images we see on our screens, including ad creatives. Pixel stuffing means placing an entire ad into a 1x1 pixel area, making it so small that it may appear as little more than a spot on a standard device screen.

Despite visitors not really seeing the ad, it still counts as a viewed impression since the creative is delivered and displayed. Additionally, multiple pixel-sized ads can be placed on a single page. Publishers who use pixel stuffing may find themselves blacklisted from reputable networks.

Ad Stacking

Ad stacking refers to multiple ads placed in the same area on a web page, with one advertisement covering the other. Since both ads are delivered, impressions are counted for each one regardless of whether they’re visible or not.

Source: Cloudflare

Scammers can use this technique to place their own ads over those approved by the publisher, consequently stealing clicks and revenue.

Ad Injection

Like stacking, ad injection typically refers to a fraudulent ad replacing an existing one without the publisher’s permission. Additionally, ad injection can also display advertisements on a web page where there previously were none. These ads aren’t controlled or reviewed and can do significant damage to a publisher’s reputation.

For example, Walmart experienced an injection attack, with a competitor’s ads replacing those on the site.

Domain Spoofing

Spoofing is a widespread type of cyber attack and can apply to web pages, emails, phone calls, and more. In ad fraud, spoofing refers to when a scammer presents themselves as a reputable publisher in the buying process.

For example, advertisers may think their ads are being placed on a reputable site like the Financial Times. In reality, the ads appear on an unknown site with bot traffic that simply impersonates the actual website.

Domain spoofing is exceptionally costly for advertisers and publishers. In 2017, the Financial Times discovered that they were losing almost $1.3 million in revenue to spoofed domains.

Cookie Stuffing

Publishers who use affiliate links are particularly at risk of cookie stuffing. Fraudsters will drop a fake cookie into a user’s browser. If that user then clicks on an ad on your site and makes a purchase, the cookie will supply false affiliate information, and the fraudster will claim your commission.

Bot Traffic

Arguably one of the more common types of ad fraud, bot traffic is generated by scripts designed to mimic user behavior. They can open sites, browse pages, and even click on ads. Due to their prevalence, bots are one of the main reasons behind the deflation of ad inventory value.

Click Farms

If you’re a publisher, you’ve likely received at least one offer of “ad safe traffic” that can be sent your way for a reasonable fee. Many of these offers come from click farms. Unlike bots, click farms consist of real people visiting your site to click on ads, download apps, and increase impressions. However, it’s an extremely poor practice that can have lasting negative consequences. It may even get your site blacklisted.

A real click farm with workers employed to browse sites and generate clicks on ads. Source: Diggit Magazine

Force Redirect

Some malicious ads automatically redirect users through one or multiple pages that contain malware, spyware, trojans, or other types of viruses and malicious software. Some may also try to trick visitors into giving up their personal information. These types of ads can have an extremely negative impact on a publisher’s reputation.

How Publishers Can Fight Ad Fraud

Fighting ad fraud isn’t easy. Publishers and advertisers are rarely even aware that they’re being affected. Unfortunately, there’s no one-size-fits-all solution, and the industry has been looking for ways to prevent ad fraud for years.

We’re going to mention a few ways publishers can fight ad fraud below. However, keep in mind that it’s always a good idea to communicate with your advertising partners if you suspect an issue. It’s better to be transparent and tackle the problem rather than risk being blacklisted.

Bot Management

A bot management system, like those provided by some content delivery networks, can help analyze visitor behavior. The system will identify bots and filter out their activity by preventing them from interacting with the website. You can also use verification solutions to avoid serving ads to non-human traffic.

Ads.txt Framework

An ads.txt file confirms which partners are authorized to buy ad inventory from the publisher. It also verifies a publisher’s ownership of a domain. The framework was implemented to minimize ad fraud by only allowing approved networks to buy inventory from the verified domain.

Unfortunately, the ads.txt framework isn’t infallible. Fraudsters have identified ways to use the framework to access accounts using the ads.txt file, selling fake inventory to approved networks while appearing legitimate. That is why publishers should always try to use multiple ways to protect themselves.

Trusted Monetization Partners

Trusted monetization partners, like rev•amp, use cutting-edge tools to help prevent ad fraud, malvertising, and similar ad-related cyberattacks. It’s critical to work with a partner that uses technology to help minimize and prevent ad fraud as much as possible, protecting both publishers and advertisers from malicious scammers.


Ad fraud is a significant issue facing publishers, advertisers, and ad networks. These fraudulent activities can cost publishers thousands in revenue while significantly affecting their relationships with networks, search engines, and advertisers.

While it’s unlikely that we’ll ever be able to prevent ad fraud completely, publishers can put certain protections in place to mitigate the risks. Implementing a bot management system and an ads.txt file can go a long way to blocking fraudsters. It’s also essential to work with a trusted monetization partner or network.

Most importantly, if you suspect that you’re the victim of ad fraud, immediately address the issue with advertisers and partners to prevent further fallout.

Senior Ad Tech
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