Never trust a file based solely on its filename. Use these steps to verify that your Winbox 3.11 executable hasn't been tampered with:
Winbox 3.11 Verified Download: A Complete Guide to Legacy MikroTik Management winbox 311 verified download
: The most secure way to get older versions is through the official MikroTik Downloads page under the Tools or WinBox tab. Never trust a file based solely on its filename