The hackers, who have not been identified, appear to bear a grudge against the company and want to undermine it by exposing users to public scrutiny.

The prospect of attacks by non-financially driven hackers pursuing publicity, blackmail or moral judgments sends shivers through the online dating and sex industry.

Reports that blackmailers armed with the data dump are contacting Ashley Madison members for extortion will reinforce concerns. For the online adult entertainment segment, which accounts for more than 10 percent of Internet traffic, the trend is particularly worrisome.

“I don’t know anyone that’s prepared for something like this,” said Joanna Angel, a famous punk porn entrepreneur who owns and sells adult films on the website Burning Angel.