SMB Security Best Practices by US-Cert

Taken from  SMB Security Best Practices

US-CERT recommends that users and administrators consider:

• disabling SMB v1 and
• blocking all versions of SMB at the network boundary by blocking TCP port 445 with related protocols on UDP ports 137-138 and TCP port 139, for all boundary devices.

US-CERT cautions users and administrators that disabling or blocking SMB may create problems by obstructing access to shared files, data, or devices. The benefits of mitigation should be weighed against potential disruptions to users. For more information on SMB, please review Microsoft Security Advisories 2696547 (link is external) and 204279 (link is external)