Malicious Google adverts have been used to deliver convincing tech-support scams that make Windows and Mac browsers appear frozen and infected. The fake warnings pressure users to call bogus support centres, where criminals may demand payment, remote access or personal information, highlighting how ordinary web adverts can be turned into highly persuasive fraud.

Netskope recorded clicks from users at 619 organisations between 31 August and 14 September, across more than 250 campaign IDs and at least 284 legitimate websites; it blocked the content, so none of those users were scammed. The software hides the address bar, disables common exit keys, slows the browser, plays sounds and adapts its presentation for Windows or macOS, while encrypting its code to evade detection. Google said it was investigating, but did not confirm that all related adverts had been removed; in many cases, holding down Escape for several seconds can close the fake warning.