They allegedly profited on deals and speculation involving the drug maker Intermune, the companies Intel and Pitney Bowes. The US Securities and Exchange Commission also sued and seeks an asset freeze.

The three targeted at least seven major international law firms that had been retained by companies to advise on deals and got into the e-mail accounts of senior lawyers at two of the firms, according to the indictment unsealed Tuesday.

NEW YORK — Three Chinese hackers made more than $4 million in illicit profits after breaking into the servers of top law firms in New York, the United States said in announcing charges and the arrest of one of the men.


The case places law firms among the widening group of targets for cybercriminals seeking to profit from insider information. Last year, federal officials broke up an international ring of hackers who allegedly infiltrated the computer servers of PRNewswire Association LLC, Marketwired, and Business Wire and stole market-moving press releases before they were published. According to the SEC, the group, which included Ukrainians and a Georgian, made more than $100 million from trading on the information.

‘‘This case of cyber meets securities fraud should serve as a wake-up call for law firms around the world,’’ Manhattan US Attorney Preet Bharara said in the statement.

The three men — Iat Hong and Chin Hung, 50, of Macau, and Bo Zheng, 30, of China — worked at a robotics company that was started by Zheng, according to the government. Hong, 26, was arrested in Hong Kong on Christmas Day and is awaiting extradition. The SEC is also seeking to freeze an account registered in Hong’s mother’s name.

In addition to the law firms, they also hacked other robotics companies, the United States said. They allegedly stole designs of a robot vacuum cleaner made by a US company.


The three generally used the same tactics to get the information, federal officials said. They would get the log-in credentials of an employee and place malware on a server that allowed them to access the e-mails of key people at the firms and companies, according to the indictment. In a one-day period in 2014, they allegedly took 10 gigabytes of confidential data from one law firm’s server.

They weren’t always successful. During one six-month period in 2015, the men allegedly tried, on more than 100,000 occasions, to break into the networks of five law firms.

The law firms weren’t identified in the complaints. The Wall Street Journal reported in March that Cravath Swaine & Moore LLP and Weil Gotshal & Manges LLP were among the targeted law firms. Neither firm responded to a request for comment on the charges.

They allegedly bought shares of Intermune based on the information gleaned from the hacked data. Though the deal didn’t close, they still made money as shares rose on media reports that the company was seeking a tie-up, the United States said. Intermune was ultimately purchased by Roche AG.