An Israeli advertising agency has been serving millions of online adverts that allow “zero-click” spyware to be used against targets, researchers at a Canadian university have said.

Citizen Lab, a digital investigations research unit at the University of Toronto, said it believed dozens of devices at the Qatari broadcaster Al Jazeera had been compromised by spyware delivered through ads run by Discover-Tech, which describes itself as a specialised digital advertising agency.

According to Citizen Lab, Discover-Tech operates a software platform called Controlium that allows its clients to “mass-profile and deanonymise” internet users then covertly hack targets with third-party spyware. Unlike infections that rely on people interacting with links or files, the spyware requires no interaction from the victim to be installed, making it a new delivery technique, Citizen Lab says.

The infections happen without a user’s knowledge, and in a matter of seconds, according to Citizen Lab.

“[The online advertising] ecosystem is being weaponised at a massive scale to profile millions of users, then silently infect targets with zero-click mercenary spyware,” the report says.

According to the report, Controlium is able to harvest a user’s identity and IP address when the user is shown a seemingly benign custom-created ad – for example, for a digital game or a telecoms service. If the user has been selected as a target for hacking, a mercenary spyware firm can then send a malicious code containing spyware to their device, the researchers say.

They say that millions of users worldwide have been served ads by Discover-Tech since 2024, including in Yemen, Brazil, Mexico and Czechia.

Related work by the research group Confiant also suggests that Discover-Tech’s ads have been shown to users of the networks of government entities in Europe and the US, as well as the UN, Nato, the international criminal court and the International Atomic Energy Agency.

“It’s disastrous that major ad vendors and organisations apparently were neither able to detect nor prevent the company’s malicious advertising operations for years,” said Wolfie Christl, a researcher at Citizen Lab. “The way the online advertising ecosystem works today is a security threat for states, the private sector, civil society and everyone else alike.”

According to Citizen Lab, Controlium acts as a “facilitator” for third-party spyware firms that have targeted “government officials, journalists, businesspeople, activists, academics and embassy workers”. Citizen Lab claims it can deliver spyware that can access everything on the device of a target, extracting messages, photos and emails, recording calls and secretly activating microphones.

The full extent of the targeting allegedly enabled by Discover-Tech is unknown. Citizen Lab’s findings join mounting evidence that the opaque arrangements underpinning the world of online advertising can be leveraged for surveillance.

“There has been a lot of buzz that online ads can be used to identify and automatically hack targets with pinpoint precision, but now for the first time, we have concrete technical evidence showing this process in action,” said Bill Marczak, a researcher at Citizen Lab.

Discover-Tech has been approached for comment.

When a user navigates to a website that shows advertisements, their details become part of a split-second programmatic auction involving dozens or hundreds of companies. These companies bid automatically to place an ad in front of that user.

These bids are based on the user’s profile, which can include information about their device and data compiled on them by tracking their activity across the web. For example, companies given the profile of a 35-year-old interested in sports betting and crypto might bid to show that individual an advertisement for an energy drink.

There is little regulation on this automated online market, and there is growing evidence that it is being exploited by malevolent actors.

Reuters has reported that billions of dollars’ worth of Meta’s ad revenue comes from ads for scams, illegal gambling, pornography and other banned content. In the US, ICE and other government agencies have bought software that uses ad tech data to track people’s movements.

“Cybersecurity agencies, regulators and lawmakers in the US, Europe and other regions must urgently step in. They must investigate the involved companies and fix the systemic risks that enable malicious ad targeting,” said Christl.