What is Malvertising? Definition, examples and how to stop it

Key facts

Attackers buy search ads on trusted software brands, so "downloading the official tool" via the top result installs the trojanized version.
Because ads rotate per user and region, the malicious version is hard for site owners and scanners to reproduce.
Malvertising frequently feeds credential phishing: the ad's landing page imitates a login rather than delivering a file.

How it reaches your organization

An employee searches for a tool, clicks the sponsored result above the genuine one, and lands on a pixel-perfect fake: a download that carries a loader, or a login page that harvests credentials, which then come back at you through email as account takeover. Malvertising and email attacks are separate channels that converge on the same goal: a foothold in your environment. Related reading: phishing, social engineering and zero-day attacks.

How to defend

Ad or DNS filtering on managed devices, a policy that software comes from vetted internal sources rather than search results, browser and OS patching to close drive-by paths, and credential monitoring, since harvested logins surface later in email-based attacks.

How Sentaro helps

Sentaro covers the convergence point: when malvertising-harvested credentials are used for mailbox takeover or the foothold pivots to internal phishing and business email compromise, Behavioral Defense flags the account acting outside its history, and Message Defense catches the credential-phish follow-ups in mail flow.

Questions we get asked.

What does malvertising mean?

Malicious advertising: using real ad networks to deliver malware or route users to phishing pages, often via sponsored search results for trusted brands.

Can you get infected without clicking the ad?

Historically yes, via drive-by exploits in browsers or plugins; modern browsers have reduced but not eliminated the risk. Most current malvertising still relies on a click and a convincing landing page.

How do we protect employees from malvertising?

Ad/DNS filtering, software sourced from vetted repositories instead of search ads, aggressive browser patching, and monitoring for the account compromise that follows harvested credentials.