MI5 made “substantial contributions” to an investigation which has seen four people – including two members of the Russian security services – charged over one of the largest data breaches in US history.
The US Justice Department announced on Wednesday that charges have been brought in relation to the 2014 attack which targeted around 500 million Yahoo accounts.
Acting Assistant Attorney General Mary McCord said: “We’re here for one of the largest data breaches in US history.
“Today we are announcing the indictment of four individuals responsible for the 2014 hacking… of Yahoo, the theft of information about at least 500 million Yahoo accounts, and use of that information to obtain the contents of accounts at Yahoo and other providers.”
FBI executive assistant director Paul Abbate said: “We are extremely grateful as well to our international partners for their assistance and support leading up to these criminal charges today.
“Those partners include Canada’s Royal Canadian Mounted Police and, as mentioned, the Toronto police service and their fugitive squad.
“As well, the United Kingdom’s MI5 made substantial contributions to the advancement of this investigation also.”
Mr Abbate added: “This indictment details how Russian federal security service officers working together with criminal hackers conspired to plan and carry out one of the largest cyber intrusions in US history.
“These perpetrators compromised the company’s networks, along with the accounts and personal information of approximately 500 million Yahoo users, and further stole millions of user contacts in order to carry out fraud schemes for their own personal financial gain and enrichment.”
Two of the arrested men are said to be Russian Federal Security Service officers, who allegedly “directed, facilitated and paid” the hackers.
“They worked with co-conspirators to hack the computers of American companies providing email and internet-related services,” Ms McCord said.
Although the Justice Department has previously charged Russian hackers with cybercrime – as well as hackers sponsored by the Chinese and Iranian governments – this is the first criminal case brought against Russian government officials.