See what was stolen from all those Facebook accounts. SAN FRANCISCO -- Facebook believes spammers, not a nation state, were behind the data breach of 30 million accounts, according to a published report. The spammers aimed to make money through deceptive advertising and masqueraded as a digital marketing company, people familiar with the company's internal investigation told the Wall Street Journal. Facebook has declined to say who was behind the hack, which was the worst security breach in its history. Reached for comment by USA TODAY on Wednesday night, Facebook pointed to last week's statement from Guy Rosen, vice president of product management.