The Pentagon on Thursday confirmed that there was a hacking attempt

this past weekend against an online financial services portal that Citigroup manages for Defense Department credit card holders.

The confirmation comes a day after Citigroup told CNBC that a "malicious actor" attempted to gain access to information for Pentagon-linked credit card accounts.

The bank had responded to CNBC's inquiry regarding an attempted hack this past weekend. The Pentagon, citing information from Citigroup, confirmed to CNBC on Thursday that there was an attack over the weekend of March 10.

The bank told the Defense Department that the attack came from a computer system that was randomly guessing cardholder account usernames and passwords.

The program hit Citigroup's Pentagon online account application more than 1.3 million times. The hackers did successfully guess 318 Pentagon cardholders' usernames and passwords, but they did not get past a secondary layer of account authentication.

"No data compromise occurred," Citi told the Pentagon.

Citi provides financial services for the Government Travel Charge Card, or GTCC, which is used by Department of Defense personnel to pay for authorized expenses when on official travel.

CitiManager is the online portal used by the Defense Department to view statements online, make payments and confirm account balances.

The Pentagon's Defense Travel Management Office oversees the processing of the GTCC.