NY Times reports today that NK may be able to make their own rocket fuel now -- one variant of hydrazine, unsymmetrical dimethylhydrazine or UDMH,
https://www.nytimes.com/2017/09/17/world/asia/north-korea-rocket-fuel-missiles.html [nytimes.com]
Pop Science earlier has a more detailed look at how their missile might work,
http://www.popularmechanics.com/military/weapons/a26857/north-korea-icbm/ [popularmechanics.com]
It's really nasty stuff...