Restrict outbound traffic to that which is necessary, and specifically deny all other traffic

Risk Level: Medium
Cloud Entity: AWS Security Group
CloudGuard Rule ID: D9.AWS.NET.09
Covered by Spectral: Yes
Category: Networking & Content Delivery

GSL LOGIC

SecurityGroup should not have outboundRules with [ protocol='ALL' and scope='0.0.0.0/0' ]

REMEDIATION

Reduce the scope of the outbound rules to just the necessary scope, protocol, and ports.
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 Outbound Rules tab
6. Identify the rules to be removed
7. Edit the Outbound rule , change the source cidr range, port, protocol or Delete the rule.
8. Click Save

From TF
Add CIDR range, port, protocol to restrict egress access from all port, protocol and range.

resource "aws_security_group" "positive2" {
	egress {
		from_port         = 3306
		to_port           = 3306
		- protocol          = "ALL"
		+ protocol          = "tcp"
		- cidr_blocks       = ["0.0.0.0/0"]  # != "0.0.0.0/0"
		+ cidr_blocks       = ["10.0.2.0/0"]
		security_group_id = aws_security_group.default.id
	}
}

From Command Line
To make sure security groups doesn't allow egress to 0.0.0.0/0 or to all port, run:

aws ec2 revoke-security-group-egress --region REGION --group-name GROUP-NAME --protocol PROTOCOL --port PORT --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://docs.aws.amazon.com/cli/latest/reference/ec2/revoke-security-group-egress.html
4. https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group

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 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 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