Security Group With Unrestricted Access To SSH

• Query id: 6e856af2-62d7-4ba2-adc1-73b62cef9cc1
• Query name: Security Group With Unrestricted Access To SSH
• Platform: CloudFormation
• Severity: Medium
• Category: Networking and Firewall
• URL: Github

Description

'SSH' (TCP:22) should not be public in AWS Security Group
Documentation

Code samples

Code samples with security vulnerabilities

Positive test num. 1 - yaml file

Resources:
  Ec2Instance:
    Type: 'AWS::EC2::Instance'
    Properties:
      SecurityGroups:
        - !Ref InstanceSecurityGroup
      KeyName: mykey
      ImageId: ''
  InstanceSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
        GroupDescription: Allow http to client host
        VpcId:
          Ref: myVPC
        SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 22
          ToPort: 22
          CidrIp: 0.0.0.0/0
        SecurityGroupEgress:
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: 0.0.0.0/0

Positive test num. 2 - json file

{
  "Resources": {
    "Ec2Instance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "ImageId": "",
        "SecurityGroups": [
          "InstanceSecurityGroup"
        ],
        "KeyName": "mykey"
      }
    },
    "InstanceSecurityGroup": {
      "Properties": {
        "SecurityGroupEgress": [
          {
            "IpProtocol": "tcp",
            "FromPort": 80,
            "ToPort": 80,
            "CidrIp": "0.0.0.0/0"
          }
        ],
        "GroupDescription": "Allow http to client host",
        "VpcId": {
          "Ref": "myVPC"
        },
        "SecurityGroupIngress": [
          {
            "ToPort": 22,
            "CidrIp": "0.0.0.0/0",
            "IpProtocol": "tcp",
            "FromPort": 22
          }
        ]
      },
      "Type": "AWS::EC2::SecurityGroup"
    }
  }
}

Code samples without security vulnerabilities

Negative test num. 1 - yaml file

Resources:
  Ec2Instance:
    Type: 'AWS::EC2::Instance'
    Properties:
      SecurityGroups:
        - !Ref InstanceSecurityGroup
      KeyName: mykey
      ImageId: ''
  InstanceSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
        GroupDescription: Allow http to client host
        VpcId:
          Ref: myVPC
        SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: 127.0.0.1/32
        SecurityGroupEgress:
        - IpProtocol: tcp
          FromPort: 80
          ToPort: 80
          CidrIp: 127.0.0.1/33

Negative test num. 2 - json file

{
  "Resources": {
    "InstanceSecurityGroup": {
      "Type": "AWS::EC2::SecurityGroup",
      "Properties": {
        "GroupDescription": "Allow http to client host",
        "VpcId": {
          "Ref": "myVPC"
        },
        "SecurityGroupIngress": [
          {
            "FromPort": 80,
            "ToPort": 80,
            "CidrIp": "127.0.0.1/32",
            "IpProtocol": "tcp"
          }
        ],
        "SecurityGroupEgress": [
          {
            "IpProtocol": "tcp",
            "FromPort": 80,
            "ToPort": 80,
            "CidrIp": "127.0.0.1/33"
          }
        ]
      }
    },
    "Ec2Instance": {
      "Type": "AWS::EC2::Instance",
      "Properties": {
        "SecurityGroups": [
          "InstanceSecurityGroup"
        ],
        "KeyName": "mykey",
        "ImageId": ""
      }
    }
  }
}