Many organizations have embraced cloud platforms now, like Amazon AWS or Microsoft Azure, whether they are using it for just a few services or moved part or all of their infrastructure there. No matter the service though, configuration isn’t foolproof and they all require specific knowledge to configure in a secure way.
In some cases we have seen these services configured in a way that isn’t best practice, which led to exposure of sensitive information, or compromises through services that should not have been exposed. In many instances there are at least some areas that can be hardened, or features enabled, to reduce risk and improve monitoring capabilities.
So, what should you be doing? We’ll take a look at Amazon AWS today, and some of the top issues.
One issue, that is seemingly pervasive, is inappropriate permissions on S3 buckets. Searches on S3 incidents will turn up numerous stories about companies exposing sensitive data due to improper configuration. How can you prevent that?
Firstly, when creating your buckets, consider your permissions very carefully. If you want to publicly share data from a bucket, consider granting ‘Everyone’ read permissions to the specific resources, instead of the entire bucket. Never allow the ‘Everyone’ group to have write permissions, on the bucket, or on individual resources. The ‘Everyone’ group applies literally to everyone, your employees and any attackers alike.
Secondly, take advantage of the logging capability of S3, and monitor the logs. This will help identify any inappropriately accessed resources, whether through inadvertently exposed buckets, or through misuse of authorization internally.
Another common issue is ports unnecessarily exposed on EC2 resources. This happens through misconfigurations in VPC NACLs or Security Groups, which act as a firewall, sometimes found configured with inbound traffic allowed to any port from any ip. NACLs and Security Groups should be configured to allow the least amount of traffic to the destination as possible, restricting by port and by ip. Don’t forget about restricting outbound traffic as well. For example, your database server probably only needs to talk to the web server and system update servers.
The last issue we’ll discuss today is the IAM, the Identity and Access Management interface. Firstly, you should be using IAM to configure users and access, instead of sharing the root account among everyone. Secondly, make sure IAM users and keys are configured correctly, with the least amount of privileges necessary for that particularly user. I also recommend requiring multifactor authentication, particularly on the root account, any users in the PowerUsers or Admins group, or any groups you have with similar permissions.
That’s all for today. And remember, the good news here is that you can configure these systems and services to be as secure as what is sitting on your local network.