CyberGlossary

Attacks & Threats

Malvertising

Also known as: Malicious advertising

Definition

The use of online advertising networks to distribute malware, exploits, or scams via legitimate-looking ads served on trusted websites.

Malvertising abuses programmatic advertising infrastructure by buying or hijacking ad slots and embedding malicious JavaScript, redirects, or exploit-kit code in the creative. Because ads are served by trusted ad networks on reputable publishers, even highly trafficked sites can unknowingly deliver attacks to their visitors. Outcomes range from drive-by downloads and exploit-kit infections to tech-support scams, scareware, and credential phishing. Defences include reputable ad blockers and DNS filtering, browser isolation, fully patched endpoints, EDR, strict click-to-play for active content, content-security policies, and education that warns users about cloned login pages and fake software updates.

Examples

  • A poisoned banner ad on a news site redirects visitors to an exploit kit that drops ransomware.
  • A fake "system update" ad lures users into downloading an info-stealer disguised as a browser patch.

Related terms