If the KB would have been made in EU or for EU market, it must follow very strict regulations and only way that oily compound could've gotten into it is from outside source. But since KB is Indian made for Indian market, then who knows what kind of materials are used in it's manufacturing. E.g Indian made PC cases (cabinets) are low quality and i wouldn't touch Indian made PSUs even with 2 meter pole.
At this point, i can't tell if the oily compound originated from outside source (e.g sweat mixed with dead skin cells + heat) or within KB itself (e.g chemicals inside plastic/PCB reacted with heat or plastic itself melted). Heat comes into play since India is one hot place where to live and ambient temps are high, especially during summer.