[plaintext]

Here the AV log, and one file in the quarantine:

URL
**External links are only visible to Support Staff****External links are only visible to Support Staff**

This url is blocked and one file was downloaded and blocked (in quarantine).

This happens 5 secs after jd update, can you check it?

I don't have other info, the downloaded file is an .exe with a very long name with cipher and characters (in a random sequence i think)

[Jiaz]

This file (executable) is not part of JDownloader/Update. Maybe you've added some links to download and one of them is this file.

[plaintext]

Ok, after that JD won't extract .rar files...

Maybe it's something about the rar plugin?

[Jiaz]

It's very likely that those archives are RAR5.
RAR5 is not yet supported out of the box. You've got to install rar5 library yourself, see
https://board.jdownloader.org/showthread.php?t=71069