Those who use their computers to save wallet file (.json file) and also use to access the internet then there is a chance that the wallet file may got infected and unusable if you are not expert at keeping your device secured and safe from viruses and malwares.
Malware installation is not because of file type, any file can be affected. The best way to get your devices or wallet devices free from malware is to avoid the malware, basic ways you can avoid malware is the main reason for this thread.