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 445 in order to reduce the attack surface and protect the EC2 instances associated with your security groups. Common Internet File System (CIFS) port 445 is used by client/server applications to provide shared access to files, printers, and communications between network nodes directly over TCP (without NetBIOS) in Microsoft Windows Server 2003 and later. CIFS is based on the enhanced version of Server Message Block (SMB) protocol for internet/intranet file sharing, developed by Microsoft.
This rule can help you with the following compliance standards:
- 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.
Allowing unrestricted inbound/ingress access on TCP port 445 (CIFS) to your Amazon EC2 instances can increase opportunities for malicious activities such as ransomware attacks, Man-in-the-Middle (MITM) and Denial of Service (DoS) attacks.
Audit
To determine if your Amazon EC2 security groups allow unrestricted CIFS access, perform the following operations:
Remediation / Resolution
To update the inbound rule configuration for your Amazon EC2 security groups in order to restrict Common Internet File System (CIFS) access to trusted entities only (i.e. authorized IP addresses and IP ranges, or other security groups), perform the following operations:
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 CIFS Access
Risk Level: Very High