I've been testing these kinds of searches every now and again for a few years now (and complaining about it on HN regularly). The malware ads are generally intermittent and won't show all of the time. That doesn't mean they don't exist.
I can assure you that for many years Google has been serving ads that link to malware for search terms like "firefox". I've seen them across different machines, different browsers, different ISPs, different OSs.
The situation with firefox seems better now but only because Mozilla is seemingly buying up all the ads for searches with "firefox" in.
That is a very big assumption that may hold for Browsers but not many other products. And even if illegitimate models are more efficient, a big business can afford a money sink for PR.
I can assure you that for many years Google has been serving ads that link to malware for search terms like "firefox". I've seen them across different machines, different browsers, different ISPs, different OSs.
The situation with firefox seems better now but only because Mozilla is seemingly buying up all the ads for searches with "firefox" in.
Here's a post about it from a year and a half ago that also links to several earlier posts along the same lines: https://news.ycombinator.com/item?id=8879229