Bennett Haselton writes: United Airlines announced that they will offer up to 1 million air miles to users who can find security holes in their website. I demonstrated a way to brute-force a user's 4-digit PIN number and submitted it to them for review, emailing their Bugs Bounty contact address on three occasions, but I never heard back from them. Read on for the rest. If you've had a different experience with the program, please chime in below.