It was not a hack. It was just a lot of doxxing. There was really nothing impressive about it.
and from the article: "Officers found 30,000 SIM cards, 240 iPhones, 150 MI phones, 2 laptops, 2 and other electrical appliances. The gadgets were plugged into a system."
[1]: https://nairobinews.nation.co.ke/wp-content/uploads/2018/08/...
[2]: https://nairobinews.nation.co.ke/news/detectives-smash-illeg...
It doesn't add up 900, only to 390.. but still.. if these guys would focus their ingenuity in something positive, they could have accomplished so much more in life.