CrossOver Support - Community Forums

I'm running Crossover through a WSL2 Linux Distro, and Windows Defender found a Trojan horse in the deb file.

I have just downloaded crossover_20.0.0-1.deb and Avast found nothing. In my humble opinion, you should not trust Windows Defender much... Lots of false positives and missing malware, compared to other solutions.

I second Silvio's comment. Going through all versions of [Linux] CrossOver for a long time and never had any warning. Neither before 20.0.0.-1.deb and never after it. Latest version of CO is 21.0.0-1.deb.
Using Windows Defender as AV and Malware detection is not a good Idea when running Windows. For decades I had always a 3rd party AV installed on my Windows OS. Now on Linux Mint as my only OS for some time. Installed AV is ESET NOD32 and no warning about malware for CrossOver there either.

Another point to observe is that .deb files are not containers of executable code for Windows and Windows Defender only checks for Windows malwares.

As AV goes, Windows Defender is fine. You're going to get occasional false positives especially when dealing with niche software like this.

You need to be aware when using any AV that the AV itself is an attack surface. The part of the AV that inspects the data can be a target for exploits, which if successful would mean that a real-time scan causes malware to execute instead of protecting against it. I've been told that Windows Defender does a good job of preventing this (I believe it runs the inspection code in a sandbox, but I'm having trouble confirming that), so it's something to be aware of if you're looking to replace it with a third-party AV.