In all versions of InDesign, the cursor appears as a pixelated box.
At this moment, InDesign CC 2017 or earlier are not compatible with macOS High Sierra.
For some people, deactivating the GPU Performance will work.
- Go to InDesign > Preferences... in the menubar (CMD + K)
- Select the tab GPU Performance
- Deactivate the option GPU Performance
- Click on OK
- Restart InDesign
Although this workaround seems to work for some people, we'll have to wait for a final fix (released by either Apple or Adobe or both). So we strongly advise you to not upgrade to macOS High Sierra 10.13, unless you really don't have a choice! Always install updates on test machines and leave production machines untouched until you are sure everything is working well on your test machine!
See this KB-article.
Apple has released an update for macOS High Sierra that fixes this annoying bug. See this KB-article for more info and the download. Or install the update using Updates in the App Store.