The publication notes that the attack on the Amex, most likely a continuation of the campaign of Middle East hackers attacking American financial institutions. A few days earlier had been attacked servers bank JPMorgan Chase, which also reported that as a result of DDoS-attacks down withdrew its IT capacity. Recall that the first attack on U.S. financial institutions began last fall, and since then, the hacker group has conducted several campaigns to attack.
However, if in the case of JPMorgan Chase for conducting attacks have assumed responsibility very specific person, place a special statement on the Pastebin.com, a case with American Express so far no one has claimed responsibility for DDoS-attack. The New York Times notes that in the case of American Express no customer data were not injured, and the attack was totally destructive, but not the spy character.
Officials from American Express said that the attack was carried out on Thursday and so far they have no evidence that the hackers were hunting for user data.