The macOS system must not process Internet Control Message Protocol [ICMP] timestamp requests.

From Apple OS X 10.13 Security Technical Implementation Guide

Associated with: CCI-000366

SV-96427r1_rule The macOS system must not process Internet Control Message Protocol [ICMP] timestamp requests.

Vulnerability discussion

ICMP timestamp requests reveal information about the system and can be used to determine which operating system is installed. Precise time data can also be used to launch time-based attacks against the system. Configuring the system to drop incoming ICMPv4 timestamp requests mitigates these risks.

Check content

To check if the system is configured to process ICMP timestamp requests, run the following command: sysctl net.inet.icmp.timestamp If the value is not set to "0", this is a finding.

Fix text

To disable ICMP timestamp responses, add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.icmp.timestamp=0

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