Demonstrate and fix front running attack (up to 3500 Gold)

[mikera]

We currently believe that CPoS is relatively resistant to front-running attacks, and that a front running attack without special resources is not feasible on the Convex network. We would like to test and verify this belief, hence the objective of this bounty is to demonstrate and hopefully fix a front running attack.

Requirements:

• Must show front running, i.e. an attacker successfully executes a transaction before an existing in-flight transaction observed on the network.
• Must be a plausible attack where attacker does not have access to special resources:
• does not have large network stake (<10%0
• does not have ability to intercept / censor arbitrary messages on the network
• does not have other unusual resources (e.g. ultra-fast global messaging)
• Client is assumed to submit transaction to a good/trusted peer. Attacker must observe the message broadcast on the network before submitting its intended front-running transaction
• Must have demonstration code that is repeatable (at least with high probability of attack success)

Bounty breakdown:

• 500 Gold for repeatable attack demonstration code
• 1000 Gold for PR to fix specific attack
• Up to 2000 Gold extra for more general solution to front running / network security