Thanks to [ethexplorer.io](https://ethplorer.io/), we can browse the DXChain and find [the transaction of 100,000,000DX that happened on the 26 Nov 2020](https://ethplorer.io/tx/0xfdef5b6f6dece6b29695b9fd8d0cadaff944876e598fd443125e1f8c2db15160#pageSize=100).
The flag is `vulncon{0xfdef5b6f6dece6b29695b9fd8d0cadaff944876e598fd443125e1f8c2db15160}`.