I have an iPod 3 running OS9. I was in Safari and clicked a rather sketchy link, which brought about a small pop-up window with another link. The only way to close the popup would have been to hit "OK" on the popup. I knew I didn't want to do that, because the wording in the popup was slightly off of being correct English, the subject matter was to get a free iPhone 6s from Google, and the website it was associated with ended in "-alert.xyz". Even if I tried to switch to another open window, it wouldn't let me and if I opened a new window, the popup showed over that window. So I was pretty certain it was some form of malware that would take me to a website that could do a lot of harm if I clicked on it. I called Apple support at my local store (They are in holiday mode now and help by phone for free.) and quickly got a simple solution. I went to Settings, then Safari, then I clicked on the link that clears the history and when I reopened Safari, the popup was gone for good. Of course, so were the other webpages I had open, but that was a small price to pay for security.