SSH access should be disabled on network security groups from the Internet

Warning: This rule will be deprecated 18 December 2023 as part of the update to Azure CIS version 2.0.0

Description

Disable SSH access on network security groups from the internet.

Rationale

The potential security problem with using SSH over the internet is that attackers can use various brute force techniques to gain access to Azure Virtual Machines. Once the attackers gain access, they can use a virtual machine as a launch point for compromising other machines on the Azure Virtual Network or even attack networked devices outside of Azure.

Remediation

1. Disable direct SSH access to your Azure Virtual Machines from the internet.
2. Choose one of the following methods to access the virtual machines for remote management:
   • Point-to-site VPN
   • Site-to-site VPN
   • ExpressRoute

References

1. https://docs.microsoft.com/en-us/azure/security/benchmarks/security-controls-v2-network-security#ns-1-implement-security-for-internal-traffic