JPMorgan Chase – one of the largest banks in the US – has suffered a huge data breach which has affected 76 million households and seven million small businesses. The size of the attack makes it one of the largest breaches discovered; in perspective in 2012 the US had approximately 115 million households in total.

According to The Guardian the breach was under way for a month before it was discovered in July. In August when the breach was disclosed JPMorgan Chase estimated only one million accounts had been affected – a tiny fraction of the actual figure.

JPMorgan Chase said customers using its websites and mobile applications - Chase.com, JPMorganOnline, Chase Mobile and JPMorgan Mobile - had been affected by the breach.

According to a post on the chase.com website the bank has started to notify its customers about the security breach. In the post the bank disclosed that customer contact information including name, address, phone number and email address and internal JPMorgan Chase information relating to customers had been compromised.

“There is no evidence that account information for such affected customers – account numbers, passwords, user IDs, dates of birth or Social Security numbers – was compromised during this attack,” the post said.

JPMorgan Chase said it has not witnessed any unusual customer fraud after the breach. It is working with government agencies the Federal Bureau of Investigation (FBI) and the US Secret Service to try to piece together how the breach took place.

Not alone
JPMorgan Chase joins a host of other US organizations hit by large-scale data breaches.

Earlier in the year US retail giant Target revealed it was hit by a huge data breach in the lead up to Christmas last year.

Target said 40 million credit and debit card accounts and personal information from approximately 70m customers was compromised in the breach.

Last month US DIY retailer The Home Depot suffered a breach after malware was used in payment data systems from April to September. It said its breach affected 56 million customer payment cards across the US and Canada.

In a statement, JPMorgan spokeswoman Trish Wexler said companies “of our size unfortunately experience cyber-attacks nearly every day. We have multiple layers of defense to counteract any threats and constantly monitor fraud levels”.