- 1. Search for the Official Sources
- DNF and Flathub are the official sources.
- 2. Check the SSL Certificate of the Website
- Irrelevant. Compromised mirrors don't really matter because if they mess with a package, it won't be signed properly anymore and the GNU/Linux distribution won't agree to install it, and will warn the user.
- 3. Check Domain TLD
- Irrelevant. If a package doesn't have a signature match, it can't be installed, plus APT, DNF, and Flatpak only use the official mirror or repo address they were originally configured for or a redirect offered by the distribution's server.
- 4. Check Domain Age
- Irrelevant. If a package signature doesn't match, it won't be installed. Who cares what mirror it came from or how recently it was added?
- 5. Look for Website Reviews
- Irrelevant. If a package signature doesn't match a signing key from the distribution or approved of and added by the user, it won't be installed.
- 6. Scan the File Download Link With Online Scanner Tool
- Mostly irrelevant. If you want to, you can scan an RPM or Debian package if you're about to install one locally, and it may not be a bad idea, but first you should try locating it from a more official source, where it will be verified and signed. If you proceed to install it, perhaps all of these tips do apply, but since most users have 1 or 2 packages like this on their system at most, it's not likely they'll get malware.
- 7. Keep an Eye on the File Extension
- On a GNU/Linux system, the user normally has to make it possible to execute a file if they simply downloaded one.
- If Wine is installed and the user is attempting to run a Windows application, this can be relevant, as are all 7 steps pointed out here, even though Wine isn't Windows and most Windows viruses fail to do their assigned task in Wine, it is a good idea to be highly skeptical of Windows software and proceed with extreme caution, if proceeding at all.