OKISZ headquarters, Budapest, 1973, János Mónus
Source of photos, article in Hungarian with more images: https://epiteszforum.hu/betonba-foglalt-alom--az-okisz-szekhaz
Translators usually don't work well with Hungarian language, but you can try to read the article: https://translate.google.com/translate?sl=auto&tl=en&u=https%3A%2F%2Fepiteszforum.hu%2Fbetonba-foglalt-alom--az-okisz-szekhaz
https://imgur.com/FEezKJ0Open linkView original on lemm.ee
Is this considered to be part of the "Brutalist School" of architecture that was popular behind the iron curtain and to a certain extent in West Germany?
Yes! You can tell by the use of exposed, "raw" (unpainted) concrete. However, I don't believe that brutalism was more popular east of the iron curtain than in the west -- there are examples all over the world, notably in London.