shared-2fa

Sometimes you have an account for a website which you share with your team so everybody can use it, but still want to enable 2FA for enhanced security. This tool helps you to share a virtual TOTP based MFA-device with your team by saving the intial seed at the parameter store of AWS SecureSystemManager.

Pricing

Using this tool will probably not produce any AWS costs for you. Storing/Getting Parameters in the ParameterStore is free. The only operations that will get charged by AWS is when you generate a token, because in the background the tool has to retrieve the parameter from the ParameterStore and because the parameters are encrypted this will make a call to KMS to get the encryption key. The first 20.000 requests per month to KMS are part of the Free Tier and after that 10.000 req/month are 0,03$. So even with a big team and lots of entries, this will propably never apear on your invoice.

IAM permissions

With this example policy one can use all features of this tool. If you want people to have only the ability to generate tokens, you can just remove the Delete and Create actions.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "ssm:PutParameter",
                "ssm:DeleteParameter",
                "ssm:GetParameter"
            ],
            "Resource": "arn:aws:ssm:eu-central-1:<your-account-id>:parameter/2fa-*"
        },
        {
            "Sid": "VisualEditor1",
            "Effect": "Allow",
            "Action": "ssm:DescribeParameters",
            "Resource": "*"
        }
    ]
}

Usage

In order to use this tool, you need to have a set of AWS API Keys in the default configuration file. If you have used the aws-cli before, you are already good to go :)

add

Create a new entry

Usage:
  shared-2fa add <name> <seed>

When enabling 2FA for an online service, you probably get an QR-Code which you could scan e.g. with the Google Authenticator app on your smartphone. Sometimes the website shows your the seed right next to the image (look for a quite long, random, alphanumeric string). If not, you have to use a barcode scanner app to get the content of the QR-Code and extract the seed out of this special URI.

delete

Delete an entry

Usage:
  shared-2fa delete <name>

generate

Generate a token for the given entry

Usage:
  shared-2fa generate <name>

list

List all available entries

Usage:
  shared-2fa list

With ❤ by codemonauts

codemonauts / shared-2fa