I have done a few of these due to an expertise in a niche within the high frequency trading industry; they weren't near 5000$, typically around 10% of that. If it's a scam, I am betting you will know really quick (if they ask for bank info etc), I always asked for a paper check, and didn't offer up much personal information. If you post the firm that contacted, someone can probably corroborate one way or another.