Default VPC security group allows unrestricted traffic
- Severity
- High
- Service
- Security groups
- Check ID
- DEFAULT_SG_OPEN
What this check finds
The default security group in a VPC should not allow any inbound or outbound traffic. Any resource assigned to the default SG inherits these permissive rules. Use purpose-specific security groups instead.
Passing looks like: Default security group restricts all traffic.
How to fix it
Remove all inbound and outbound rules from the default security group.
AWS CLI
aws ec2 revoke-security-group-ingress --group-id SG_ID --ip-permissions IP_PERMISSIONSFor outbound rules:
aws ec2 revoke-security-group-egress --group-id SG_ID --ip-permissions IP_PERMISSIONSRepeat for each rule, and assign resources to purpose-built security groups.
Names in capitals are placeholders for your own resource. Review a command before you run it.
AWS console
EC2 → Security Groups → find default → Inbound/Outbound rules → Delete all.
Compliance controls it is evidence for
A failing result counts against these controls in KloudLytics; a passing one is evidence towards them. How compliance mapping works
| Framework | Controls |
|---|---|
| CIS AWS Foundations Benchmark v5.0.0 |
|
| PCI-DSS v4.0.1 |
|
| HIPAA Security Rule |
|
| SOC 2 — Trust Services Criteria |
|
| NIST SP 800-53 Rev5 (Moderate) |
|
| NIST Cybersecurity Framework 2.0 |
|
| ISO/IEC 27001:2022 Annex A |
|
Checked on every scan
KloudLytics runs this check each time it scans a connected AWS account, through a read-only role, and lists every affected resource with its region. On Pro and Business a fix is written for the specific resource rather than the general case above. The exact access it needs