Control: 6.2 Ensure that SSH access is restricted from the internet

Description

Disable SSH access on network security groups from the Internet.

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

Disable direct SSH access to your Azure Virtual Machines from the Internet. After direct SSH access from the Internet is disabled, you have other options you can use to access these virtual machines for remote management:

Note: By default, SSH access from internet is not enabled.

Usage

Run the control in your terminal:

powerpipe control run azure_compliance.control.cis_v140_6_2

Snapshot and share results via Turbot Pipes:

powerpipe login
powerpipe control run azure_compliance.control.cis_v140_6_2 --share

SQL

This control uses a named query:

with network_sg as (
  select
    distinct name sg_name
  from
    azure_network_security_group nsg,
    jsonb_array_elements(security_rules) sg,
    jsonb_array_elements_text(sg -> 'properties' -> 'destinationPortRanges' || (sg -> 'properties' -> 'destinationPortRange') :: jsonb) dport,
    jsonb_array_elements_text(sg -> 'properties' -> 'sourceAddressPrefixes' || (sg -> 'properties' -> 'sourceAddressPrefix') :: jsonb) sip
  where
    sg -> 'properties' ->> 'access' = 'Allow'
    and sg -> 'properties' ->> 'direction' = 'Inbound'
    and (sg -> 'properties' ->> 'protocol' ilike 'TCP' or sg -> 'properties' ->> 'protocol' = '*')
    and sip in ('*', '0.0.0.0', '0.0.0.0/0', 'Internet', 'any', '<nw>/0', '/0')
    and (
      dport in ('22', '*')
      or (
        dport like '%-%'
        and split_part(dport, '-', 1) :: integer <= 22
        and split_part(dport, '-', 2) :: integer >= 22
      )
    )
)
select
  sg.id resource,
  case
    when nsg.sg_name is null then 'ok'
    else 'alarm'
  end as status,
  case
    when nsg.sg_name is null
      then sg.title || ' restricts SSH access from internet.'
    else sg.title || ' allows SSH access from internet.'
  end as reason
  
  , sg.resource_group as resource_group
  , sub.display_name as subscription
from
  azure_network_security_group sg
  left join network_sg nsg on nsg.sg_name = sg.name
  left join azure_subscription sub on sub.subscription_id = sg.subscription_id;

Control: 6.2 Ensure that SSH access is restricted from the internet

Description

Remediation

Usage

SQL

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