TL;DR1. User controls the ram and can program the VM2. Flag can be retrieved only in **emode**3. **emode** can be entered by guessing 14 bits from /dev/urandom4. Brute force those 14 bits and write the flag in the last 64-bytes of the ram5. After the timeout, the VM will print the last 64-bytes of the ram, giving us the flag
Full writeup: https://sectt.github.io/writeups/CSAW21-quals/ncore/README