Malvertising
Malicious online adverts that deliver scams or malware, even on reputable sites.
Malvertising is the use of online advertising to deliver scams or malware. Because ad space on legitimate websites is bought and served through automated networks, criminals can slip poisoned adverts onto otherwise reputable pages — meaning a trustworthy site is no guarantee that the ad on it is safe.
Some malicious ads try to install software or trigger fake virus warnings; others are simply the entry point to a phishing page or a fake shop, dressed up as a too-good deal or an urgent alert. A particularly common version buys search-engine ads for well-known brands, so a sponsored result at the top of a search leads to a look-alike scam site rather than the real one. The defences are habit-based: be wary of clicking adverts for deals that seem improbable, reach important sites by typing the address or using a bookmark rather than a sponsored link, and keep your browser and devices updated. If an advert manufactures urgency or wants you to sign in or hand over payment, treat it exactly as you would an unsolicited message. Reading a web address carefully, as our scam-website guide describes, catches most of the destinations these ads lead to.