2.2.1.2 Ensure Network Access Rules are set to Deny-by-default

Information

Restricting default network access provides a foundational level of security to networked resources. To limit access to selected networks, the default action must be changed.

Resources using Virtual Network interfaces should be configured to deny-by-default all access from all networks (including internet traffic). Access can be granted to traffic from specific Azure Virtual networks, allowing a secure network boundary for specific applications to be built. If necessary, access can also be granted to public internet IP address ranges to enable connections from specific internet or on-premises clients.

For all traffic inbound from- and outbound to- the internet, a NAT Gateway is recommended at minimum, and ideally all traffic flows through a security gateway device such as a firewall. Security gateway devices will provide an additional level of visibility to inbound and outbound traffic and usually perform advanced monitoring and response activity such as intrusion detection and prevention (IDP), and deep packet inspection (DPI) which help detect activity indicating vulnerabilities and threats.

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

Impact:

All allowed networks and protocols will need to be allow-listed which creates some administrative overhead.

Implementing a deny-by-default rule may result in a loss of network connectivity. Careful planning and a scheduled implementation window allowing for downtime is highly recommended.

See Also

https://workbench.cisecurity.org/benchmarks/19304

Item Details

Category: CONFIGURATION MANAGEMENT, CONTINGENCY PLANNING, PLANNING, PROGRAM MANAGEMENT, SYSTEM AND SERVICES ACQUISITION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|CM-7, 800-53|CP-6, 800-53|CP-7, 800-53|PL-8, 800-53|PM-7, 800-53|SA-8, 800-53|SC-7, CSCv7|13.3

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