Ensure that your Amazon EC2 security groups don't allow unrestricted inbound access (i.e. 0.0.0.0/0 or ::/0) on TCP ports 20 and 21 in order to protect against attackers that use brute force methods to gain access to the EC2 instances associated with your security groups. TCP ports 20 and 21 are used for data transfer and communication by the File Transfer Protocol (FTP) client-server applications.
This rule can help you with the following compliance standards:
- PCI
- APRA
- MAS
- NIST4
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 FTP access to your Amazon EC2 instances via security groups can increase opportunities for malicious activities such as brute-force attacks, FTP bounce attacks, spoofing, and packet capture attacks.
Audit
To determine if your Amazon EC2 security groups allow unrestricted FTP access, perform the following operations:
Remediation / Resolution
To update the inbound rule configuration for your Amazon EC2 security groups in order to restrict FTP access to trusted entities only (i.e. authorized IP addresses and IP ranges, or other security groups), perform the following operations:
References
- AWS Documentation
- Amazon EC2 security groups for Linux instances
- Work with security groups
- Security group rules for different use cases
- Authorize inbound traffic for your Linux instances
- AWS Command Line Interface (CLI) Documentation
- ec2
- describe-security-groups
- revoke-security-group-ingress
- authorize-security-group-ingress