I just wanted to agree with this. I turned down a job a number of years ago that offered me great thing eventually but you'll be 'just helping push an existing project over the line for a few weeks'. Complete red flag.

There will be other IT security jobs. If you really want one, you should just turn down both offers and wait for one you really want. Good programmers are rare and you can probably wait around for something you like better.

Edit: Also, don't believe promises regarding payrises after 6 months, shares in the company, healthcare, etc. If it's not on the table when you negotiate the contract, be sure you'll be happy when the promises fail to materialise.