Hacker behind 2012 attacks on LinkedIn and Dropbox was in regular contact with alleged SEC hacker, according to DOJ filing

The hacker was arrested in Czech Republic in October 2016

Two hackers who separately attacked LinkedIn and the US Securities and Exchange Commission (SEC) had worked together and also shared resources.

In a new court filing on Tuesday, the US Department of Justice (DOJ) claimed that Yevgeniy Nikulin, a Russian national, accused of stealing nearly 117 million usernames and passwords from LinkedIn, Formspring, and Dropbox in 2012 was in contact with Oleksandr Ieremenko, a Ukrainian man, charged for allegedly hacking the US Securities and Exchange Commission (SEC) in 2016 and 2017.

Nikulin was arrested in the Czech Republic in October 2016 before being extradited to the US in 2018.

In 2012, the US Secret Service had seized a hard drive belonging to Ieremenko, which revealed further evidence related to Nikulin case.

"The contents of Ieremenko's hard drive as a whole show that Ieremenko and Nikulin worked together on (1) the stolen news release, (2) stolen LinkedIn information, and (3) other uncharged hacking activity," the DOJ filing states, according to CyberScoop.

"In general, the government views Ieremenko and Nikulin as co-conspirators. In 2012, specifically, they were both part of a small cohort of Ukrainian and Russian hackers — a criminal clique — whose members consulted with one another and sometimes shared resources."

According to the DOJ, Nikulin had also tried to sell stolen credentials on a Russian internet forum.

Last year, Nikulin was ordered to undergo a psychiatric evaluation after he refused to communicate with government attorneys about his case. Attorneys told the court that the Russian man was communicating about other matters without any difficulty.

However, his lawyers argued that Nikulin suffers from post-traumatic stress disorder (PTSD) related to an abusive father and his brother's suicide.

In May, US District Judge William Alsup ruled that Nikulin was medically fit to face trial in the case.

Nikulin has pleaded not guilty to charges against him, which include aggravated identity theft, conspiracy, computer intrusion, and trafficking in unauthorised access devices.

The DOJ has not publically charged Ieremenko in connection with stealing user credentials from LinkedIn or any other social media platform.

The SEC, however, indicted Oleksandr Ieremenko last year, along with another Ukrainian national Artem Radchenko, for allegedly hacking its EDGAR filing system and stealing trade secrets from hundreds of companies' filings. The two hackers were charged with wire fraud conspiracy, securities fraud conspiracy, and computer fraud conspiracy.

In another civil complaint, SEC claimed that a network of securities traders based in Russia, Ukraine and the US received stolen information from hackers and used it illegally to make money by selling off or snapping-up securities before the filings were made public.