Here is a simple way to block viber ads:
- First use this post to find where your hosts file is.
- Edit the file as administrator and add the following lines:
127.0.0.1 ads.viber.com 127.0.0.1 ads.aws.viber.com 127.0.0.1 ads-d.viber.com
Hint: You can use notepad++ to edit the file and it will automatically switch to administrator mode.