It is in standard tuning but with each of the strings tuned down to their flats:
eb
Decided to write this first bit down because nobody else had. IM pretty sure it is 100% correct.
eb-------------------------------------------------------------------|
Bb-------------------------------------------------------------------|
Gb-------------------------------------------------------------------|
Db--11-11-11-11--3-3-5-5----6--6--7--8--8--8-10-10-11-11--4--4-------|
Ab--11-11-11-11--3-3-5-5----6--6--7--8--8--8-10-10-11-11--4--4-------|
Eb--9--9--9--9---1-1-2-2----4--4--5--6--6--6--8--8--9--9--2--2-------|
Simple riff, sounds good, enjoy.