Pool Together 2.0

Smart contracts will often have an owner or admins to designate entities with special privileges to make modifications to the smart contract. Specifically, the pool admins have the privilege to commit and open draws, set fee fractions, set beneficiary of the fee, pause and unpause the contract, and add and remove admins. Consequently, if the last admin is ever removed, no new admin can ever be added. Exploit Scenario: Admins may take advantage of calling rewardAndOpenNextDraw() in the following scenarios: 1) Admins can try to wait until a favorable block to call rewardAndOpenNextDraw() since they control the entropy. 2) Admins can decide to never call rewardAndOpenNextDraw(), in which case the interest is locked forever. 3) Admins can delay calling rewardAndOpenNextDraw() for an extremely long period of time, waiting for most other users to exit so that the odds of winning the lottery are heavily in their favor.