Asteria 2 contains an article of mine on the twelfth house. In that article I also discuss curses in more detail since they're an area covered by this house, but the nature and the spirit of the house are also detailed. In short, I mentioned the twelfth house facilitates a person to be cursed and at the same time it is part of an individual's personal shielding against curses whenever the native is in need of spiritual protection.
The eleventh house is considered that of the Higher Self and so it would usually be thought as the house that protects from curses, but in that article I already said it should be studied in parallel with the twelfth just as I said of the twelfth in the book. As a brief recap, the Higher Self cannot be represented by the chart for it transcends it, let alone by a sole astrological house. Therefore, the eleventh house merely covers beneficial influences a person receives from their Higher Self while the twelfth covers the malefic ones - I explained in the article while those are necessary and other hints can be found it at least one other article I wrote in this book. Hence the need for both of them to be studied in parallel.
But what about curses? For a person to suffer from the effects of a magical curse both their eleventh and twelfth houses must allow for that curse to affect its target. They can do that to more or less degree depending on circumstances that are too vast to discuss without endless digressions. I laid out general considerations for this in the article. It can go as far as in a case I've been observing for some time now and I will detail further.