While the rest of the world engaged in merriment and good cheer, hackers used the holidays to attack a United States research group that puts out a daily newsletter on security issues.

On Saturday, hackers who say they are members of the collective known as Anonymous claimed responsibility for crashing the Web site of the group, Stratfor Global Intelligence Service, and pilfering its client list, e-mails and credit card information in an operation they say is intended to steal $1 million for donations to charity. The hackers posted a list online that they say contains Stratfor’s confidential client list as well as credit card details, passwords and home addresses for some 4,000 Stratfor clients. The hackers also said they had details for more than 90,000 credit card accounts. Among the organizations listed as Stratfor clients: Bank of America, the Defense Department, Doctors Without Borders, Lockheed Martin, Los Alamos National Laboratory and the United Nations.

The group also posted five receipts online that it said were of donations made with pilfered credit card details. One receipt showed a $180 donation from a United States Homeland Security employee, Edmund H. Tupay, to the American Red Cross. Another showed a $200 donation to the Red Cross from Allen Barr, a recently retired employee from the Texas Department of Banking. Neither responded to requests for comment.

Mr. Barr told The Associated Press that on Friday he discovered that $700 had been transferred from his account to charities including the Red Cross, Save the Children and CARE, but that he had not been aware that the transfer was tied to a breach of Stratfor’s site.