CitiBanamex witch is owned by Citibank in the US was only affected last Sunday, they tried to hack in to the ATM'S and they just shut down, no trans actions or money withdrawals were possible, this was corrected on Monday morning, I went to the bank yesterday morning and asked them about it.
CitiBanamex and the Bancomer do not participate in the countries money transfer program between banks that is what was hacked, you need a special PIN number in order to transfer money to or from your account with CitiBanamex to another bank's account.
Transferring from the Citibank US account to the Mexican CitiBanamex account is and was not affected at all, for now just go to the teller and have them do what you need to do instead of using the ATM's, specially the ones that are in shopping malls or stores.
navegator