I was visiting a popular site, and clicked to resize its window. I noticed that there was a popunder from HR Block that seemed to be downloading something to my computer. Popunders scare me because they can be under my view. Is this an unwarranted fear?
No. Ads can indeed deliver an unwanted payload to your machine.
Hopefully you’re running some type of AV solution so you are protected from such tactics.
Just check for any windows appearing in the task bar without your permission.
SuperAdBlocker is a good popup blocker, just make sure that you get the lifetime version if you buy it.
If a website wanted to download and execute a malicious file through an exploit, why go to the trouble of creating a popup?
The site could not be malicious itself, but it gets income from pop ups and/or pop unders, who could then deliver malicious content to an unsuspecting user.
There have been cases where malware writers actually purchased ad-space on popular websites only to infect anyone who visits the page.
Thanks for all the interesting replies. It seems hard for antivirus programs to keep up with these new malicious ideas these days. Popunders do delay detection because you might be too busy with the window on top to even notice.
Best thing to do to prevent this would be to add any site that comes in a pop up (or under) and all the common ad revenue websites to your hosts file.