Cross peering connectivity refers to the ability of two different Virtual Private Clouds (VPCs) to communicate with each other using their respective IP addresses. By default, cross peering connectivity is not allowed between VPCs, and it has to be explicitly enabled by configuring VPC peering. However, in some cases, EC2 instances may be misconfigured to allow cross peering connectivity, which can pose a security risk. This can happen if an EC2 instance is configured to allow traffic from IP addresses outside its VPC, or if it is part of a security group that allows traffic from a peered VPC.
- Review the security group rules associated with each EC2 instance to ensure that they do not allow incoming traffic from IP addresses outside its VPC.
- If the EC2 instance is part of a security group that allows traffic from a peered VPC, review the security group rules associated with that peered VPC to ensure that they do not allow incoming traffic from the EC2 instance's VPC.
- Use VPC flow logs to monitor network traffic and identify any unauthorized cross-peering activity.
- If cross peering connectivity is required for specific use cases, configure VPC peering and implement appropriate security measures to restrict access between the peered VPCs.
Note: Remediation steps provided by Lightlytics are meant to be suggestions and guidelines only. It is crucial to thoroughly verify and test any remediation steps before applying them to production environments. Each organization's infrastructure and security needs may differ, and blindly applying suggested remediation steps without proper testing could potentially cause unforeseen issues or vulnerabilities. Therefore, it is strongly recommended that you validate and customize any remediation steps to meet your organization's specific requirements and ensure that they align with your security policies and best practices.