Half contacts are not mine

Recently all my contacts got deleted from my iPhone 6S, so, as always, I restored them from iCloud.com

But what I did not notice at first is that about a half of the contacts are not mine: all names and numbers are unknown to me and all of them are of different country (not sure which one, names seemed kirgiz). No, I don't share my apple id or my phone with anyone, it is completely independent from anybody except me and I defenitely did not add them.

I changed my password for Apple id and restored my contacts from the distant date (because if I restored them from a recent one all these contacts were still there). It helped, they are gone. But what the ****? Did anybody ever faced this kind of issue?