Ashley Madison, an online dating website that helps married people cheat on their spouses, has been hit by a cyber-attack that has apparently compromised a large swath of the company's data and customers' private information.

The hack, first reported by online security blogger Brian Krebs, released large caches of data onto the Internet, including the company's user databases, financial records and other proprietary information, according to Krebs.

On its homepage, the site touts having more than 37 million anonymous members, as well as a "Trusted Security Award" and "100% discreet service."

In a statement, Avid Life Media, the parent company of Ashley Madison, condemned the attack as unprovoked and criminal.

"We were recently made aware of an attempt by an unauthorized party to gain access to our systems," the statement says. "We apologize for this unprovoked and criminal intrusion into our customers' information."

A manifesto from the hacker or hacking group The Impact Team says that Avid Life Media must take down Ashley Madison or they will release their customers' records and information. Photo Credit: Brian Krebs / Krebs on Security

The hacker or hackers threatened to "release customer records, including profiles with all the customers' secret sexual fantasies and matching credit card transactions, real names and addresses, and employee documents and emails" if the website is not taken down, according to the statement.

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According to the manifesto published by the hacker or hackers -- who go by the name The Impact Team -- the company's "Full Delete" feature that allows members to completely erase their profile information from AshleyMadison.com for $19 does not actually work.

"Full Delete netted ALM $1.7 million in revenue in 2014. It's also a complete lie," the hacking group wrote. "Users almost always pay with credit card; their purchase details are not removed as promised, and include real name and address, which is of course the most important information the users want removed."

The Impact Team also demanded that Avid Life Media's other online website, Established Men, be taken down. The company also owns CougarLife.

According to Avid Life Media, the breach has been contained, with the company adding "we have been able to secure our sites, and close the unauthorized access points. We are working with law enforcement agencies, which are investigating this criminal act. Any and all parties responsible for this act of cyberterrorism will be held responsible."

Ashley Madison, which launched in 2001 and is based in Toronto, uses the slogan "Life is short. Have an affair."