Control: 6.3 Ensure no SQL Databases allow ingress 0.0.0.0/0 (ANY IP)

Description

Ensure that no SQL Databases allow ingress from 0.0.0.0/0 (ANY IP).

SQL Server includes a firewall to block access to unauthorized connections. More granular IP addresses can be defined by referencing the range of addresses available from specific datacenters.

By default, for a SQL server, a Firewall exists with StartIp of 0.0.0.0 and EndIP of 0.0.0.0 allowing access to all the Azure services.

Additionally, a custom rule can be set up with StartIp of 0.0.0.0 and EndIP of 255.255.255.255 allowing access from ANY IP over the Internet.

In order to reduce the potential attack surface for a SQL server, firewall rules should be defined with more granular IP addresses by referencing the range of addresses available from specific datacenters.

By default, setting Allow access to Azure Services is set to ON allowing access to all Windows Azure IP ranges.

Remediation

From Console

1. Login to Azure console, go to SQL servers
2. For each SQL server
3. Click on Firewall / Virtual Networks under security section from side bar
4. Set Allow access to Azure services to OFF
5. Set firewall rules to limit access to only authorized connections