Hosted files are regularly scanned with anti-malware software. If malware is found, you will be informed by email which will contain a list of files, which may be infected. After one week files are automatically cleaned or, if it contains only malware, moved to quarantine.
If file was recognized fail-positively, it wouldn’t be deleted – it’s moved to quarantine and can be restored from there. Please contact us if it happened, so we can investigate it thoroughly.