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Inbound ICMP access is restricted

ec2

Description

Reduce the probability of a breach by checking EC2 security groups for inbound rules that allow unfettered access to host using the Internet Control Message Protocol (ICMP), a protocol commonly used to troubleshoot TCP/IP networks and deliver IP packets, and restrict access.

Rationale

Malicious activity, such as denial-of-service (DoS) attacks and Smurf/Fraggle attacks, can occur when permitting unfettered access to this port.

Remediation

From the console

Follow the Security group rules docs to learn how to restrict access to host using the ICMP.

From the command line

  1. Run describe-security-groups with a filter to expose security groups that allow access to host using ICMP.

    describe-security-group.sh

        aws ec2 describe-security-groups
    	    --filters Name=ip-permission.protocol,Values=icmp Name=ip-permission.cidr,Values='192.0.2.0/24'
    	    --query 'SecurityGroups[*].{Name:GroupName}'