Some of the biggest tech companies in the world served ads on a website featuring images of child abuse, helping to fund its operations. It shines a light into the dark corners of digital advertising.

Sometimes you come across an image online that's so horrifying you can't unsee it. For Krzysztof Franaszek, it happened at work.

Franaszek runs the advertising research firm Adalytics based in the US. Recently, he was studying where ads for the US Department of Homeland Security end up online, and the project took him to an image-sharing website called ImgBB. There, Franaszek uncovered something sickening: sexually explicit images of a very young child, with adverts for Fortune 500 companies running alongside them.

He immediately reported the content to the US Federal Bureau of Investigation (FBI), the Department of Homeland Security (DHS), and child safety organisations. The Canadian Centre for Child Protection – one of those Franaszek alerted – says it found at least 35 images flagged by Adalytics on the site that meet its classification of child sexual abuse material (CSAM). The Centre says it notified ImgBB, and the images were taken down. An FBI spokesperson says the bureau reviews all allegations of criminal conduct but does not comment on tips from the public. The DHS did not respond to questions.

The more Franaszek dug, the clearer the problem became – and his findings raise questions about how the adverts you see online may also be inadvertently pumping large sums of money into undesirable, and at times illegal, corners of the internet.

According to a new report from Adalytics, advertising systems run by companies including Google, Amazon and Microsoft have inadvertently funnelled money to the owners of a website hosting illegal images of child sex abuse. In addition to CSAM, Adalytics documented ads for more than 70 large organisations and Fortune 500 companies running alongside hardcore adult pornography, including MasterCard, Nestlé, Starbucks, Unilever and even the US Government. "Many advertisers whose ads appeared on this website probably had no idea that they were funding this kind of content," Franaszek says.

On 7 February 2025, US Senators Marsha Blackburn and Richard Blumenthal sent letters to Amazon, Google and other ad tech companies mentioned in the report, demanding answers about whether this problem represents a widespread issue across the internet. "The dissemination of [child sexual abuse material] is a heinous crime that inflicts irreparable harm on its victims," the letter to Google reads. "Where digital advertiser networks like Google place advertisements on websites that are known to host such activity, they have, in effect, created a funding stream that perpetuates criminal operations and irreparable harm to our children."

While a few images of child abuse on a single website have alarmed many both inside and outside the industry, they also provide a glimpse of some of the wider problems afflicting the inscrutable world of digital advertising. Most people who use the internet will be familiar with the clamour of digital ads fighting for their attention. They are the product of a system so vast and complex that even the companies who run it don't always know where their money is going. For years, critics have warned that the tech industry will unwittingly line the pockets of bad actors across the web without serious regulatory oversight. Lawmakers are still catching up.

Meanwhile, it is relatively easy for anyone to set up a website that can make money from ad networks. "It doesn't cost much to operate a website that serves a few million images per month," Franaszek says.

Google, Amazon and Microsoft insist they are committed to fighting online child sexual exploitation and abuse. All three companies say they have now banned ImgBB and its subsidiary site IBB from their advertising systems.

"We have zero tolerance when it comes to content promoting child sexual abuse and exploitation and both of the accounts in question are terminated," a Google spokesperson told the BBC. "Our teams are constantly monitoring Google’s publisher network for this type of content and we refer information to the appropriate authorities."

Ads are the fuel that powers the internet. The best estimates say spending on digital advertising reached an all-time high of $694bn (£559bn) in 2024. The marketing industry brings in untold sums for its clients, and the majority of ads are served on legal, appropriate sites. Sometimes, advertisers have a direct relationship with the platforms that run their adverts and commercials. But most of the time, the process is far more complex.

Almost every time you see an ad online, it's the result of a chain of dozens of platforms and services – some competing, others working together – in an automated process that plays out in fractions of a second. Advertisers usually don't pick the websites that show their ads. Instead, advertisers pay an "ad network" whose business is to find the most suitable audience on the most suitable site.

Amazon, Google and Microsoft all run ad networks of their own, but Google's are the largest by far. It's so dominant, in fact, that the company is currently fighting allegations of operating an illegal monopoly. Google disputes this and argues it faces steep competition in the digital advertising business.

These ad networks have untold millions of websites in their inventories. When a network serves an ad, the website gets paid. But anyone can plug their website into the ad networks and start making money. That means it's up to Google and other tech companies to do their due diligence to ensure they don't run ads on websites that fund criminal enterprises or damage brands' reputations.

But research by Adalytics and others suggests Google and the ad tech industry have sent advertising money from clients including US senators and multinational corporations to a long list of questionable websites, in ad campaigns that add up to tens of billions of........

© BBC