What is malvertising, and how is it stopped?

What is malvertising?

The Trustworthy Accountability Group, TAG, published its Malvertising Taxonomy (opens in a new tab) to give the industry shared terms. Version 2.0, released in April 2024, says the common element is the use of the ad creative, "including pixels, code, intended landing pages, and/or other aspects of creative assets," or another weak point in the supply or demand chain, to harm the end user. The Canadian Centre for Cyber Security (opens in a new tab) puts it more simply: "Malvertising injects malicious code into legitimate online advertisements."

TAG's Certified Against Malvertising guidelines (opens in a new tab) define the malware itself broadly: "any malicious software impacting a computer or device (e.g. phone, tablet, connected device, or router) without user consent," including spyware, adware, phishing and unwanted changes to system settings. Version 7.0 of the guidelines, released in July 2026, renamed the program from Certified Against Malware to Certified Against Malvertising without materially changing its requirements.

How do malicious ads enter the supply chain?

There are two routes. In the first, the bad actor is the buyer. TAG notes that "Malicious actors may pay digital advertising networks to display the infected ads on various websites," while the networks and sites "may remain unaware." Cloaking helps here: the taxonomy describes an auditor seeing a creative for furniture while targeted users see an investment scam. In the second route, the ad or its landing page belonged to an honest advertiser and was compromised by someone outside the supply chain.

Search ads are a route too. The FBI's Internet Crime Complaint Center warned in December 2022 (opens in a new tab) that criminals buy ads in search results that link to "a webpage that looks identical to the impersonated business's official webpage," with downloads that are malware or forms that collect logins and financial details. Brand impersonation sits close to domain spoofing, but the target is the reader rather than the buyer.

What harm does malvertising cause readers?

The direct harm is to the person on the page. The Cyber Centre's ransomware playbook says "When a user clicks the ad, malware spreads to their device," and adds that "Some malvertising does not even rely on user interactions and can distribute malicious code simply by being displayed." The reader did nothing wrong, which makes it a supply chain problem.

TAG's scam categories show the range of harm beyond malware. Phishing destinations trick users into revealing personal information "by mimicking a trusted entity such as a browser or bank." Financial scams entice users to part with money through organizations that lack the qualifications they claim. Service scams can "endanger a user's health, life, or safety" by delaying real treatment.

Honest advertisers are harmed too when their landing page or brand is the one abused. The FBI's advice to users, to check the URL before clicking and to type a business's address instead of searching for it, shows the cost: readers learn to distrust ads.

How do publishers and SSPs block malvertising?

TAG's certification spreads the work across roles. Exchanges, SSPs, ad networks and DSPs are intermediaries, and they carry the heaviest duties. They must "employ effective malvertising detection and removal services across all their advertising assets and landing pages prior to and throughout the duration of a campaign execution," and must tag creatives delivered through OpenRTB with their company name, TAG ID and creative ID, so a bad ad can be traced to its source.

Ad servers scan as well. Google Ad Manager's policy violations page (opens in a new tab) says "Google scans creatives to prevent malware," that a flagged creative "may be paused or deactivated," and that a deactivated creative "won't be reactivated in the future," so the publisher has to fix it and traffic a new one. Across companies, TAG's AdSec Threat Exchange (opens in a new tab) lets intermediaries and security vendors share malvertising intelligence "on a near real-time basis." The transparency files help too: buyers.json and sellers.json name who sits on each side of a transaction.

What should a buyer do if its ads are hijacked?

First work out which kind of hijack it is. If the brand's own landing page was hacked, the ads are the delivery route for someone else's code, and Google's ads will be disapproved under its Compromised sites policy (opens in a new tab), which defines a compromised site as one "whose code has been manipulated to act in ways that benefit a third party." If someone else is running ads that impersonate the brand, the fix is reporting and warning customers. If an honest creative was altered in delivery, the trail runs through the buying platform and its partners.

For impersonation, the FBI advises businesses to use domain protection services that flag similar new domains and to tell customers where to find legitimate downloads.

What does a malvertising response look like on a real plan?

Where does planning stage review fit next to malvertising controls?

Malvertising controls work on ads in flight. A planning review works earlier, on the sites and selling paths a plan will use, and neither replaces the other.

What should a buyer ask partners about malvertising?