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Insecure service configuration - SSH

Description​

The SSH service is not filtered by the Firewall to avoid external attacks and possible intrusions through this service.

Impact​

Attempt to access the server through brute force attacks or 0-day exploits.

Recommendation​

Securely configure the vulnerable service so that it can only be accessed by authorized users.

Threat​

External attacker without credentials.

Expected Remediation Time​

⌚ 60 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base​

  • Attack vector: N
  • Attack complexity: L
  • Privileges required: N
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: N
  • Availability: N

Temporal​

  • Exploit code madurity: X
  • Remediation level: O
  • Report confidence: X

Result​

  • Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:X/RL:O/RC:X
  • Score:
    • Base: 5.3
    • Temporal: 5.1
  • Severity:
    • Base: Medium
    • Temporal: Medium

Code Examples​

Compliant code​

The service only allows safe access to certain users

name: "myhost""
  AddressFamily: any
  AllowAgentForwarding: false
  AllowTcpForwarding: true
  ListenAddress: {{ ansible_default_ipv4.address }}:{{ ssh_port | default('22') }}
  PubkeyAuthentication: true
//Firewall configuration
hosts: myhost.com
  vars:
    ansible_port: "{{ ssh_port | default('22') }}"
  remote_user: sven
  become: true
  roles:
    - hostnames
    - users
    - ssh
    - my.firewall
  firewall_allowed_tcp_ports:
    - 80
    - 443
    - 5930

Non compliant code​

There is a resource with an SSH configuration allowing any address

name: "myhost""
  AddressFamily: any
  AllowTcpForwarding: true
  ListenAddress: any

Requirements​

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