[clamav] Virus signatures licensing
ClamAV is antivirus software and it uses virus signatures to detect malware. Most malicious software is non-free so there might be non-free signatures in the database.
IIUC virus signature are just small strings unique to the virus not who9le chuncks of code and thus considered too trivial to be copyrightable. Or it looks for heuristics. tries to create these files in this location, ergo most likely bad. Again not the actual code from the virus. Virus signatures aren't executed. They are a set of conditions to match against.