CVE-2020-0796. Scan HOST/CIDR with nmap script smb-protocols.nse and grep SMB version 3.11.

check-smb-v3.11.sh

#!/bin/bash
if [ $# -eq 0 ]
  then
    echo $'Usage:\n\tcheck-smb-v3.11.sh TARGET_IP_or_CIDR'
    exit 1
fi

echo "Checking if there's SMB v3.11 in" $1 "..."

nmap -p445 --script smb-protocols -Pn -n $1 | grep -P '\d+\.\d+\.\d+\.\d+|^\|.\s+3.11' | tr '\n' ' ' | replace 'Nmap scan report for' '@' | tr "@" "\n" | grep 3.11 | tr '|' ' ' | tr '_' ' ' | grep -oP '\d+\.\d+\.\d+\.\d+'

if [[ $? != 0 ]]; then
    echo "There's no SMB v3.11"
fi