PUP.Optional.Softonic refers to the Softonic Downloader, an adware-supported bundler.
The downloader uses manipulative UI options to prompt users to install further adware that is difficult to uninstall.
Softonic had previously included a toolbar with their download that required admin privileges, and changed the user’s home page to softonic.com.
Some software previously included by Softonic has been considered actively malicious.
Common infection method
Softonic Downloader is found on Softonic affiliated downloads at en.softonic.com.
In most cases, the built-in uninstallers and uninstall guides are far from complete. It usually takes a full Threat Scan with Malwarebytes Anti-Malware and some additional tinkering to get back the user’s preferred browser settings.