Check your Amazon EC2 security groups for inbound rules that allow unrestricted access (i.e. 0.0.0.0/0 or ::/0) on TCP port 22 and restrict the access to trusted IP addresses or IP ranges only in order to implement the Principle of Least Privilege (POLP) and reduce the attack surface. TCP port 22 is used for secure remote login by connecting an SSH client application with an SSH server.
This rule can help you with the following compliance standards:
- CISAWSF
- PCI
- APRA
- MAS
- NIST4
For further details on compliance standards supported by Conformity, see here.
This rule can help you work with the AWS Well-Architected Framework.
This rule resolution is part of the Conformity Security & Compliance tool for AWS.
Exposing the Secure Shell (SSH) port 22 to the Internet can increase opportunities for malicious activities such as hacking, Man-In-The-Middle attacks (MITM), and brute-force attacks, therefore it is strongly recommended to configure your Amazon EC2 security group rules to limit inbound traffic on TCP port 22 to known and trusted IP addresses only.
Audit
To determine if your Amazon EC2 security groups allow unrestricted SSH access, perform the following actions:
Remediation / Resolution
To update the inbound rule configuration for your Amazon EC2 security groups in order to restrict SSH access to trusted entities only (i.e. authorized IP addresses and IP ranges, or other security groups), perform the following actions:
References
- AWS Documentation
- Amazon EC2 security groups for Linux instances
- Work with security groups
- Security group rules for different use cases
- Authorize inbound traffic for your Linux instances
- AWS Command Line Interface (CLI) Documentation
- ec2
- describe-security-groups
- revoke-security-group-ingress
- authorize-security-group-ingress
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You are auditing:
Unrestricted SSH Access
Risk Level: Very High