Another to caution not using the ATM machines at GIG or GRU.

This has been a problem for many years now.

I would suggest exchanging some of your currency to R$ (BRL) before you fly, and withdraw what you need on the advice of hotel management, or friends after you arrive.

Even so advise the Fraud Department of your bank with your travel dates, look out for spoof machines when there, suspicious "eyes" following you around or near the ATM, and avoid ( if you can ) large withdrawls in incredibly bulging wallets.

The best method of carrying cash, c cards, and documents is a hidden waist band or purse, worn inside your shirt or pants.