To be absolutely clear I have no reason to think Filezilla Portable has been directly effected.
That said, starting with 3.9.0.5 Filezilla claims that updates to the next version can not be done automatically and directs users to download the installer from sourceforge... the installer for which is laden with malware and scamware which attempts to trick users into installing it.
The original author has been made aware of this and has chosen either self-delusion or outright lies... likely the latter considering the way updates were disallowed for the 3.9.0.5 version. He has