Where are the properties of goods processed when synchronizing with 1s?

Question

1C-Bitrix

Hello.
Standard synchronization between Bitrix and 1C is used.
There was a need to check the properties that come from 1s.
What you want: we check the properties that came from 1s, if we find the right one, for example, let's call it Activity, then, depending on the value (Y, N), we set the corresponding activity for the product. The question arose, where is the processing of properties during synchronization?
Or maybe you can transfer the activity of the product from 1s in some specific parameter, so as not to touch the synchronization on the side of the site?