AWS NACL allows ingress from 0.0.0.0/0 to port 21

Description

Network Access Control List (NACL) is stateless and provides filtering of ingress/egress network traffic to AWS resources. We recommend that NACLs do not allow unrestricted ingress access to port 21. Removing unfettered connectivity to remote console services, such as FTP, reduces a server's exposure to risk.

Code Example

Resources:  
  InboundRule:
    Type: AWS::EC2::NetworkAclEntry
    Properties:
       NetworkAclId:
         Ref: MyNACL
       RuleNumber: 200
       Protocol: 6
       RuleAction: allow
-      CidrBlock: 0.0.0.0/0
+      CidrBlock: 10.0.0.0/32
       PortRange:
         From: 21
         To: 21

Remediation

CloudFormation

Rule Details

Field	Value
ID	IAC-0277
Severity	LOW
IaC Type	Terraform
Frameworks	Terraform
Checkov ID	CKV_AWS_229

References

• Checkov Rule

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