The macOS system must be configured to disable Bonjour multicast advertising.

From Apple OS X 10.13 Security Technical Implementation Guide

Part of SRG-OS-000095-GPOS-00049

Associated with: CCI-000381

SV-96319r1_rule The macOS system must be configured to disable Bonjour multicast advertising.

Vulnerability discussion

To prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports/protocols on information systems.Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., VPN and IPS); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the operating system must support the organizational requirements, providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues.Bonjour multicast advertising must be disabled on the system.

Check content

To check if Bonjour multicast advertising has been disabled, run the following command: /usr/bin/sudo /usr/bin/defaults read /Library/Preferences/com.apple.mDNSResponder | /usr/bin/grep NoMulticastAdvertisements If an error is returned, nothing is returned, or "NoMulticastAdvertisements" is not set to "1", this is a finding.

Fix text

To configure Bonjour to disable multicast advertising, run the following command: /usr/bin/sudo /usr/bin/defaults write /Library/Preferences/com.apple.mDNSResponder.plist NoMulticastAdvertisements -bool true The system will need to be restarted for the update to take effect.

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