JPMorgan said Thursday that cybercriminals gathered information on more than 80 million account holders as part of a massive bank hack this summer.

The revelation follows news back in August that hackers had infiltrated seven of the country's largest banks, using sophisticated malware to burrow into their computer systems and manipulate records.

At JPMorgan (JPM), the hackers got contact information for 76 million households and 7 million small businesses, including names, addresses, phone numbers and email addresses, as well as "internal JPMorgan Chase information relating to such users."

Related: What you need to know about the big bank hack

But the bank said that the hackers didn't get any account information -- account numbers, user IDs, dates of birth or Social Security numbers -- and that it hasn't seen "any unusual customer fraud related to this incident."

"The Firm continues to vigilantly monitor the situation and is continuing to investigate the matter," JPMorgan said in a securities filing, adding that it is cooperating with law enforcement.

JPMorgan said anyone who uses its online services were affected by the hack. That includes its website and smartphone app. The bank did not immediately clarify to CNNMoney whether customers who only do in-person banking were spared.

Although it appears that the hackers haven't been able to access bank accounts, they could still cash in by selling email addresses and other personal information to spammers.

The source of this summer's attack still isn't clear. Some analysts have pointed to hackers Russia, though the evidence is only circumstantial.

Related: FBI investigating hack on JPMorgan

Hackers from Russia and eastern Europe are often top FBI suspects in cyberattacks. The timing of the hack raised suspicions given the mounting tensions between Russia and the West over Ukraine and economic sanctions.

In a letter to shareholders earlier this year, JPMorgan said it planned to deploy over 1,000 people and budget $250 million annually to focus on cybersecurity.

Cybersecurity: How safe are you?

CNNMoney's Jose Pagliery contributed reporting.