Service control policies (SCPs) are a type of organization policy that you can use to manage permissions in your organization.

SCPs offer central control over the maximum available permissions for all accounts in your organization.

SCPs help you to ensure your accounts stay within your organization’s access control guidelines

1)Prevent IAM users and roles from making specified changes, with an exception for a specified admin role

{    
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "DenyAccessWithException",
      "Effect": "Deny",
      "Action": [
        "iam:AttachRolePolicy",
        "iam:DeleteRole",
        "iam:DeleteRolePermissionsBoundary",
        "iam:DeleteRolePolicy",
        "iam:DetachRolePolicy",
        "iam:PutRolePermissionsBoundary",
        "iam:PutRolePolicy",
        "iam:UpdateAssumeRolePolicy",
        "iam:UpdateRole",
        "iam:UpdateRoleDescription"
      ],
      "Resource": [
        "arn:aws:iam::*:role/*"
      ],
      "Condition": {
        "StringNotLike": {
          ""Principal": { "AWS": "arn:aws:iam::*:user/AWSReservedSSO_AWS_Console_Global_Administrator*" }"
        }
      }
    }
  ]
}

2)Deny account from leaving the organization: When the account leaves an organization, it is no longer bound by the controls established within that organization.

This SCP can be used to prevent someone from moving an account to a different organization that has a set of different controls that are not as restrictive, and there is, therefore a risk of someone making undesired changes.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Deny",
            "Action": [
                "organizations:LeaveOrganization"
            ],
            "Resource": "*"
        }
    ]
}

1. Require an MFA

SCP forbids any AWS user from using any service without:

1. Setting up an MFA device.

2. Signing in using MFA. Any user that signs in without MFA must not be allowed to manage any resource on AWS.

{
            "Sid": "DenyAllExceptListedIfNoMFA",
            "Effect": "Deny",
            "NotAction": [
                "iam:CreateVirtualMFADevice",
                "iam:EnableMFADevice",
                "iam:GetUser",
                "iam:ListMFADevices",
                "iam:ListVirtualMFADevices",
                "iam:ResyncMFADevice",
                "sts:GetSessionToken",
                "iam:ChangePassword",
                "iam:GetUser"
            ],
            "Resource": "*",
            "Condition": {
                "BoolIfExists": {
                    "aws:MultiFactorAuthPresent": "false"
                }
            }
        }
    ]
}

4)Prevent using Root user to perform any action

As an additional layer of protection, you can set up Service Control Policy to deny access to AWS resources from the root user.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "RestrictEC2ForRoot",
      "Effect": "Deny",
      "Action": [
        "*"
        ],
      "Resource": [
        "*"
      ],
      "Condition": {
        "StringLike": {
          "aws:PrincipalArn": [
            "arn:aws:iam::*:root"
          ]
        }
      }
    }
  ]
}

OR 

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Condition": {
        "StringLike": {
          "aws:PrincipalArn": "arn:aws:iam::*:root"
        }
      },
      "Action": "*",
      "Resource": "*",
      "Effect": "Deny",
      "Sid": "DenyRootUser"
    }
  ]
}

5)Prevent users from deleting Amazon VPC flow logs

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Action": [
        "ec2:DeleteFlowLogs",
        "logs:DeleteLogGroup",
        "logs:DeleteLogStream"
      ],
      "Resource": "*"
    }
  ]
 }

6)Prevent external sharing

The following SCP prevents users from creating resource shares that allow sharing with principals that are outside of the sharing user's organization.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Deny",
            "Action": [
                "ram:CreateResourceShare",
                "ram:UpdateResourceShare"
            ],
            "Resource": "*",
            "Condition": {
                "Bool": {
                    "ram:RequestedAllowsExternalPrincipals": "true"
                }
            }
        }
    ]
}

7)Prevent users from accepting resource share invitations from external accounts outside your organization

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Deny",
            "Action": "ram:AcceptResourceShareInvitation",
            "Resource": "*"
        }
    ]
}

8) Require a Tag on specified created resource

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "DenyCreateSecretWithNoProjectTag",
      "Effect": "Deny",
      "Action": "secretsmanager:CreateSecret",
      "Resource": "*",
      "Condition": {
        "Null": {
          "aws:RequestTag/Project": "true"
        }
      }
    },
    {
      "Sid": "DenyRunInstanceWithNoProjectTag",
      "Effect": "Deny",
      "Action": "ec2:RunInstances",
      "Resource": [
        "arn:aws:ec2:*:*:instance/*",
        "arn:aws:ec2:*:*:volume/*"
      ],
      "Condition": {
        "Null": {
          "aws:RequestTag/Project": "true"
        }
      }
    },
    {
      "Sid": "DenyCreateSecretWithNoCostCenterTag",
      "Effect": "Deny",
      "Action": "secretsmanager:CreateSecret",
      "Resource": "*",
      "Condition": {
        "Null": {
          "aws:RequestTag/CostCenter": "true"
        }
      }
    },
    {
      "Sid": "DenyRunInstanceWithNoCostCenterTag",
      "Effect": "Deny",
      "Action": "ec2:RunInstances",
      "Resource": [
        "arn:aws:ec2:*:*:instance/*",
        "arn:aws:ec2:*:*:volume/*"
      ],
      "Condition": {
        "Null": {
          "aws:RequestTag/CostCenter": "true"
        }
      }
    }
  ]
}