Check your EC2 security groups for inbound rules that allow unrestricted access (i.e. 0.0.0.0/0 or ::/0) to any uncommon TCP and UDP ports and restrict access to only those IP addresses that require it in order to implement the principle of least privilege and reduce the possibility of a breach. An uncommon port can be any TCP/UDP port that is not included in the common services ports category, i.e. other than the commonly used ports such as 80 (HTTP), 443 (HTTPS), 20/21 (FTP), 22 (SSH), 23 (Telnet), 3389 (RDP), 1521 (Oracle), 3306 (MySQL), 5432 (PostgreSQL), 53 (DNS), 1433 (MSSQL) and 137/138/139/445 (SMB/CIFS).
This rule can help you with the following compliance standards:
For further details on compliance standards supported by Conformity, see here.
This rule can help you work with the AWS Well-Architected Framework.
This rule resolution is part of the Conformity Security & Compliance tool for AWS.
Allowing unrestricted (0.0.0.0/0 or ::/0) inbound/ingress access to uncommon ports can increase opportunities for malicious activity and the risk of data loss through multiple types of attacks (brute-force attacks, Denial of Service (DoS) attacks, etc).
To determine if your EC2 security groups allow unrestricted ingress access to uncommon ports, perform the following:
Remediation / Resolution
To update your EC2 security groups inbound configuration in order to restrict access to specific entities (IP addresses, IP ranges or other security groups), perform the following:
- AWS Documentation
- Amazon EC2 security groups for Linux instances
- Control traffic to EC2 instances with security groups
- Authorize inbound traffic for your Linux instances
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You are auditing:
Unrestricted Security Group Ingress on Uncommon Ports
Risk level: High