Server Message Block (SMB) Protocol Version 1 Enabled (uncredentialed check)
Info Nessus Plugin ID 96982
Synopsis
The remote Windows host supports the SMBv1 protocol.
Description
The remote Windows host supports Server Message Block Protocol version 1 (SMBv1). Microsoft recommends that users discontinue the use of SMBv1 due to the lack of security features that were included in later SMB versions. Additionally, the Shadow Brokers group reportedly has an exploit that affects SMB; however, it is unknown if the exploit affects SMBv1 or another version. In response to this, US-CERT recommends that users disable SMBv1 per SMB best practices to mitigate these potential issues.
Solution
Disable SMBv1 according to the vendor instructions in Microsoft KB2696547. Additionally, block SMB directly by blocking TCP port 445 on all network boundary devices. For SMB over the NetBIOS API, block TCP ports 137 / 139 and UDP ports 137 / 138 on all network boundary devices.