2.3.3.9 Ensure Content Caching Is Disabled

Information

Starting with 10.13 (macOS High Sierra), Apple introduced a service to make it easier to deploy data from Apple, including software updates, where there are bandwidth constraints to the Internet and fewer constraints or greater bandwidth exist on the local subnet. This capability can be very valuable for organizations that have throttled and possibly metered Internet connections. In heterogeneous enterprise networks with multiple subnets, the effectiveness of this capability would be determined by how many Macs were on each subnet at the time new, large updates were made available upstream.This capability requires the use of mac OS clients as P2P nodes for updated Apple content. Unless there is a business requirement to manage operational Internet connectivity and bandwidth, user endpoints should not store content and act as a cluster to provision data.

Content types supported by Content Caching in macOS

The main use case for Mac computers is as mobile user endpoints. P2P sharing services should not be enabled on laptops that are using untrusted networks. Content Caching can allow a computer to be a server for local nodes on an untrusted network. While there are certainly logical controls that could be used to mitigate risk, they add to the management complexity. Since the value of the service is in specific use cases, organizations with the use case described above can accept risk as necessary.

Solution

Graphical Method:

Perform the following steps to disable Content Caching:

- Open System Settings
- Select General
- Select Sharing
- Set Content Caching to disabled

Terminal Method:

Run the following command to disable Content Caching:

$ /usr/bin/sudo /usr/bin/AssetCacheManagerUtil deactivate

The output will include Content caching deactivated

Profile Method:

Create or edit a configuration profile with the following information:

- The PayloadType string is com.apple.applicationaccess
- The key to include is allowContentCaching
- The key must be set to <false/>

Impact:

This setting will adversely affect bandwidth usage between local subnets and the Internet.

See Also

https://workbench.cisecurity.org/benchmarks/15550

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-7, CSCv7|9.2

Plugin: Unix

Control ID: 4fbd45782d95fd9c8ba1408e81ec3dfadfbb3219f257561bfe07d6a15962049d