Alshabaab did not fund this attack.. The guy left with his own group from Somalia to Kenya... That is how Kenya security is so weak..Remember the man who led this attack at the west gate mall was abu khaybar... He was arrested Ina Godane for months and he left Somalia 6 hours after they killed Ibrahim afghan. They called him murtad and they were pursuing to kill him like they did al-amriki.... Now they are praising his actions and welcome him as member of Alshabaab..
here is what sayful adl wrote about abu khaybar. https://twitter.com/sayfuladl