Tags: random 

Rating:

tl;dr:
1. Notice that 32 bytes of random seed is added together byte-by-byte lowering the entropy significantly
2. Collect single result for known timestamp
3. Brute-force 12 bits of the seed sum

Full writeup: https://github.com/p4-team/ctf/tree/master/2019-11-14-dragon-finals/drow_number

Original writeup (https://github.com/p4-team/ctf/tree/master/2019-11-14-dragon-finals/drow_number).