Locky and Co led me to make my local shares read only. Because there are only movies and series, it's not a big disadvantage of comfort. Now I created a share with read/write, only used for moving data between PCs. It's is cleared with a cronjob every night. But is it a security issue, e g if malware can save itself there and infect other PCs?
Of course it IS A SECURITY ISSUE. Read-only is safe - regardless of protocol : FTP, NFS or CIFS/SMB. But write/alter access does means a way greater responsibility: you need at least a stream-in antivirus, autorun names ban and many other restrictions. IP restrictions does not count : everything can be hacked, remember.