Speaking at a press conference at Toronto Police Headquarters, Acting Staff Superintendent Bryce Evans said Ashley Madison's parent company Avid Life Media was offering a 500 000-Canadian-dollar (around R5m) reward for information leading to the arrest of the hackers.

Ashley Madison - a Canadian-based company that, since 2001, has acted as a dating service for people who wish to have extramarital affairs - has been trying to secure its data ever since the leak was reported last month.

A group calling itself Impact Team is thought to be behind the theft of the details of over 32 million accounts, Evans said.

He also provided more details on how the hack was discovered on July 12, when Avid Life Media employees logged in to their computers and were confronted by a "threatening message" from the hackers, accompanied by AC/DC's hit song Thunderstruck .

The hackers demanded that Avid Life Media shut down immediately two of its websites - Ashley Madison and Established Men - threatening to release account information on the site users.

Evans said that on July 19 the hackers released the details of two clients, one from Ontario, the other from Massachusetts.

Despite the efforts by Toronto police and an internet security company hired by Avid Life Media, on August 17 the hackers released Ashley Madison's entire client list.

Evans said that release was accompanied with another message, entitled "Time's up!"

"We have explained the fraud, deceit, and the stupidity of ALM and their members," the Impact Group message said. "Now everyone gets to see their data."

The hackers claimed the site created thousands of fake female accounts to entice men.

"90-95% of actual users are male," the message said, "chances are your man signed up to the world's biggest affair site, but never had one."

Evans said hackers sent a third message on August 20, accompanied by the release of email messages of Avid Life Media's CEO Noel Biderman.

Evans also confirmed that credit card data was included in the original 9.7 gygabytes data dump released by the hackers via the Tor internet network.

One of the largest data breaches

He said that investigators believed this was limited to the last four digits of the main card number. Police are strongly advising victims of the hack to review their accounts, Evans said.

Evans said police were investigating a series of "spin-off crimes" related to the hack.

"Criminals have already engaged in online scams by claiming to provide access to the leaked websites," he said.

"The public needs to be aware that by clicking on these links you are exposing your computers to malware, spyware, adware and viruses."

Evans also said police have received reports of extortion rackets involving Ashley Madison clients, with criminals threatening to expose them or offering to erase their names from the database for a certain fee. Evans said no one could delete the clients' names from the data dump.

"This hack is one of the largest data breaches in the world and is very unique on its own in that it exposed tens of millions of people's personal information," he added.

-News24.com