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EC2 instance does not allow ingress from the Internet to TCP port 6379 (Redis)

ec2_instance_port_redis_exposed_to_internet
Service: ec2Severity: critical
OfficialBuilt-inVerified
Categories:internet-exposed
Resource Type:AwsEc2Instance

EC2 instances with security groups permitting Internet access to Redis on TCP 6379 are identified.

Exposure is assessed using public IP assignment and subnet reachability to reflect how broadly the service can be contacted.

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Risk

Exposed Redis allows remote access to cached data and secrets, reducing confidentiality. Unauthorized commands (SET, DEL, FLUSHALL, config changes) can corrupt or erase data, harming integrity. Internet scanning and abuse can exhaust memory and disrupt service, degrading availability and enabling lateral movement.

Run this check with Prowler

Run in Prowler Cloud
Run
prowler aws --checks ec2_instance_port_redis_exposed_to_internet

Recommendation

Apply least privilege network access: restrict Redis to trusted sources or VPC-only, place instances in private subnets, and avoid public IPs.

Layer controls with NACLs and host firewalls, enforce authentication and TLS on Redis, and use VPN/bastion or proxies to broker access.

Remediation

CLI

aws ec2 revoke-security-group-ingress --group-id <SECURITY_GROUP_ID> --protocol tcp --port 6379 --cidr 0.0.0.0/0

Terraform

# Terraform: restrict Redis (6379) from Internet
resource "aws_security_group" "<example_resource_name>" {
  name   = "<example_resource_name>"
  vpc_id = "<example_resource_id>"

  ingress {
    from_port   = 6379
    to_port     = 6379
    protocol    = "tcp"
    cidr_blocks = ["10.0.0.0/8"] # Critical: not 0.0.0.0/0 or ::/0; restrict to trusted range
  }
}

NativeIaC

# CloudFormation: restrict Redis (6379) from Internet
Resources:
  <example_resource_name>:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Restrict Redis ingress
      VpcId: <example_resource_id>
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: 6379
          ToPort: 6379
          CidrIp: 10.0.0.0/8  # Critical: restrict source CIDR (not 0.0.0.0/0 or ::/0) to block Internet access

Other

1In the AWS Console, go to EC2 > Security Groups
2Select the security group attached to the affected instance
3Open the Inbound rules tab and click Edit inbound rules
4Find any rule allowing TCP port 6379 from 0.0.0.0/0 or ::/0
5Delete the rule, or change the source to a specific trusted CIDR or security group
6Click Save rules

Check Code

from prowler.lib.check.models import Check, Check_Report_AWS
from prowler.providers.aws.services.ec2.ec2_client import ec2_client
from prowler.providers.aws.services.ec2.lib.instance import get_instance_public_status
from prowler.providers.aws.services.ec2.lib.security_groups import check_security_group
from prowler.providers.aws.services.vpc.vpc_client import vpc_client


class ec2_instance_port_redis_exposed_to_internet(Check):
    # EC2 Instances with Redis port 6379 open to the Internet will be flagged as FAIL with a severity of medium if the instance has no public IP, high if the instance has a public IP but is in a private subnet, and critical if the instance has a public IP and is in a public subnet.
    def execute(self):
        findings = []
        check_ports = [6379]
        for instance in ec2_client.instances:
            report = Check_Report_AWS(metadata=self.metadata(), resource=instance)
            report.status = "PASS"
            report.status_extended = f"Instance {instance.id} does not have Redis port 6379 open to the Internet."
            is_open_port = False
            if instance.security_groups:
                for sg in ec2_client.security_groups.values():
                    if sg.id in instance.security_groups:
                        for ingress_rule in sg.ingress_rules:
                            if check_security_group(
                                ingress_rule, "tcp", check_ports, any_address=True
                            ):
                                # The port is open, now check if the instance is in a public subnet with a public IP
                                report.status = "FAIL"
                                (
                                    report.status_extended,
                                    report.check_metadata.Severity,
                                ) = get_instance_public_status(
                                    vpc_client.vpc_subnets, instance, "Redis"
                                )
                                is_open_port = True
                                break
                        if is_open_port:
                            break
            findings.append(report)
        return findings

References