id: limit-ssh-group

info:
  name: Limit SSH Users Group Access
  author: pussycat0x
  severity: unknown
  description: |
    Limiting SSH user group access enhances security by restricting login permissions to authorized groups, reducing the attack surface and preventing unauthorized access.
  remediation: |
    Ensure only necessary users are listed in AllowUsers within /etc/ssh/sshd_config, then restart the SSH service.
  reference:
    - https://vishalraj82.medium.com/hardening-openssh-security-37f5d634015f
    - https://cloud.ibm.com/docs/ssh-keys?topic=ssh-keys-granting-ssh-access-to-a-user
  metadata:
    verified: true
  tags: audit,config,ssh,auth

javascript:
  - pre-condition: |
      isPortOpen(Host,Port);
    code: |
      var m = require("nuclei/ssh");
      var c = m.SSHClient();
      c.Connect(Host,Port,User,Pass);
      const sshConfig = c.Run('cat /etc/ssh/sshd_config')
      sshConfig
      let result = "";
       if (!sshConfig.includes('AllowGroups')){
      result += "Limit SSH Users Group Access; ";
      }
      else{
      exit();
      }
      result

    args:
      Host: "{{Host}}"
      Port: "22"
      User: "{{usernames}}"
      Pass: "{{passwords}}"

    matchers:
      - type: dsl
        dsl:
          - "success == true"

    extractors:
      - type: dsl
        dsl:
          - response
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