An affidavit filed by FBI special agent Nathan Shields also alleged that Park was behind the theft of $81 million from Bangladesh Bank, the central bank of that country, in February 2016. One glaring omission was the fact that an NSA exploit used to craft WannaCry had been leaked on the Web by a group known as the Shadow Brokers in April 2017.
He was also accused of being behind numerous other unspecified break-ins at various private and government institutions.
Park was alleged to have worked for a North Korean front company known as Chosun Expo; some of the employees in branches of the firm abroad also did private work for clients. Park was said to have worked with a group in Dalian, China.
Park was alleged to have a role in creating a worm known as Brambul that affected Windows computers and "could spread through self-replication by infecting new victim systems via brute force attacks on the victim’s Server Message Block protocol. SMB is a method that Microsoft systems use to share files on a network".
The person behind WannaCry being charged does nothing to help my own legal case. Reason I'm so happy about it is because poor reporting lead to many believing i was responsible, which has consistently caused me massive problems.— MalwareTech (@MalwareTechBlog) September 7, 2018
The attack on Sony Pictures came because of the release of a film titled The Interview which poked fun at North Korean leader Kim Jong-Un.
The attack on Bangladesh Bank involved targeting the networks of local banks in that country, using the SWIFT system that banks use to conduct financial transactions.
Apart from these specific hacks, the affidavit also claimed that Park and his associates had targeted American defence contractors, one university, academic researchers, and energy companies worldwide using spear-phishing emails.
The affidavit also mentioned the WannaCry attack in great detail but did not mention the fact that a leaked NSA exploit, known as Eternal Blue, had been used to create the ransomware. However, it made one mention of the Shadow Brokers, the group that stole and then leaked the NSA exploit, along with others, on the Web in April 2017.
British security researcher Marcus Hutchins brought an end to the havoc created by WannaCry, by registering a domain that he found with the code of the malware.
Hutchins is currently in Milwaukee in the US state of Wisconsin, awaiting trial on charges that he wrote and helped distribute a banking trojan known as Kronos, which is unrelated to the charges laid against Park.
Hutchins was arrested by the FBI in Las Vegas on 2 August 2017 after he had boarded a plane to leave the US after attending the annual DEFCON security conference.
The FBI affidavit against Park said it was "intended to show merely that there is sufficient probable cause for the requested complaint and arrest warrant and does not purport to set forth all of my knowledge of the government’s investigation into this matter."