Ensure no security groups allow ingress from 0.0.0.0/0 to SSH (TCP:22)

Risk Level: Critical
Cloud Entity: AWS Security Group
CloudGuard Rule ID: D9.AWS.NET.01
Covered by Spectral: Yes
Category: Networking & Content Delivery

GSL LOGIC

SecurityGroup should not have inboundRules with [scope =  '0.0.0.0/0' and port<=22 and portTo>=22]

REMEDIATION

Removing unfettered connectivity to remote console services, such as SSH, reduces a server's exposure to risk.
From Portal

1. Login to the AWS Management Console and open Amazon VPC console https://console.aws.amazon.com/vpc/home
2. In the navigation pane, choose Security Groups.
3. For each security group, perform the following:
4. Select the security group
5. Click the Inbound Rules tab
6. Identify the rules to be removed
7. Edit the inbound rule , change the source cidr range or Delete the rule.
8. Click Save

From TF
Add CIDR range to restrict ingress access to port 22.

resource "aws_security_group" "test" {
	name        = "allow_tls4"
	description = "Allow TLS inbound traffic"
	
	ingress {
		description = "TLS from VPC"
		from_port   = 22
		to_port     = 22
		protocol    = "tcp"
		-   cidr_blocks = ["0.0.0.0/0"]
		+   cidr_blocks = ["10.92.168.0/28"]
	}
}

From Command Line
To make sure security groups doesn't allow ingress from 0.0.0.0/0 to SSH (TCP:22), run:

aws ec2 revoke-security-group-ingress --region REGION --group-name GROUP-NAME --protocol PROTOCOL --port 22 --cidr 0.0.0.0/0

References

1. https://d0.awsstatic.com/whitepapers/compliance/AWS_CIS_Foundations_Benchmark.pdf
2. https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html
3. https://awscli.amazonaws.com/v2/documentation/api/latest/reference/ec2/revoke-security-group-ingress.html?highlight=ingress
4. https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group#ingress

AWS Security Group

A security group acts as a virtual firewall for your instance to control inbound and outbound traffic. When you launch an instance in a VPC, you can assign up to five security groups to the instance. Security groups act at the instance level, not the subnet level. Therefore, each instance in a subnet in your VPC could be assigned to a different set of security groups. If you don't specify a particular group at launch time, the instance is automatically assigned to the default security group for the VPC.

Compliance Frameworks

• AWS CIS Controls V 8
• AWS CIS Foundations v. 1.0.0
• AWS CIS Foundations v. 1.1.0
• AWS CIS Foundations v. 1.2.0
• AWS CSA CCM v.3.0.1
• AWS CSA CCM v.4.0.1
• AWS CloudGuard Best Practices
• AWS CloudGuard Network Alerts for default VPC components
• AWS CloudGuard SOC2 based on AICPA TSC 2017
• AWS CloudGuard Well Architected Framework
• AWS HIPAA
• AWS HITRUST
• AWS HITRUST v11.0.0
• AWS ISO 27001:2013
• AWS ISO27001:2022
• AWS ITSG-33
• AWS LGPD regulation
• AWS MAS TRM Framework
• AWS MITRE ATT&CK Framework v10
• AWS MITRE ATT&CK Framework v11.3
• AWS NIST 800-171
• AWS NIST 800-53 Rev 4
• AWS NIST 800-53 Rev 5
• AWS NIST CSF v1.1
• AWS PCI-DSS 3.2
• AWS PCI-DSS 4.0
• CloudGuard AWS All Rules Ruleset
• CloudGuard AWS Dashboards
• CloudGuard AWS Default Ruleset