The FBI has formally accused Russian agents of hacking during the US election campaign in an extraordinary report.
A 13-page dossier details how “Russian intelligence services actors” compromised a political party twice and information from its servers were leaked to the press.
It does not name names but comes after a vast cache of Democratic Party e-mails was published by Wikileaks during the election.
The report by the FBI and Department of Homeland Security (DHS) is the most detailed set of hacking allegations against Russia so far by the US government.
It was published last night as an international row blew up over the US decision to expel 35 Russian diplomats and draw up new sanctions.
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The US expelled 35 Russian diplomats in response to hacking attacks
“These actions were taken to respond to Russian harassment of American diplomats,” a US official said.
But Russia has branded hacking accusations “absolutely groundless” as its UK embassy posted a Twitter meme calling Obama a ‘lame duck’.
And a spokesman for Russian President Vladimir Putin vowed retaliation, warning sanctions could cause “significant discomfort” for US diplomats in Russia.
The report was published alongside a joint statement by the FBI, Department of Homeland Security and Director of National Intelligenc.
The statement said: “This activity by Russian intelligence services is part of a decade-long campaign of cyber-enabled operations directed at the U.S. Government and its citizens.
“A great deal of analysis and forensic information related to Russian government activity has been published by a wide range of security companies.
“The U.S. Government can confirm that the Russian government, including Russia’s civilian and military intelligence services, conducted many of the activities generally described by a number of these security companies.”
The bulk of the alleged “malicious cyber activity” was said to take the form of sophisticated “spearphishing”.
This involves sending e-mails that appear to be from a known contact but are actually from a hacker.
“In some cases, RIS actors masqueraded as third parties, hiding behind false online personas designed to cause the victim to misattribute the source of the attack,” the report claimed.
The report said two Russian intelligence “actors” – APT28 and APT29 – infiltrated a “US political party” in summer 2015 and spring 2016.
The first sent “emails containing a malicious link to over 1,000 recipients, including multiple U.S. Government victims”, the report said.
“Using the harvested credentials, APT28 was able to gain access and steal content, likely leading to the exfiltration of information from multiple senior party members,” the report said.
“The U.S. Government assesses that information was leaked to the press and publicly disclosed.”
Hacking attempts “likely associated” with Russian intelligence are continuing, the report claimed, with one allegedly launched in November just days after the US election.
The report goes on to give cyber-security advice to government officials.
Last night Russia’s embassy in the US tweeted: “Accusations of #Russia interfering with #US presidential elections are absolutely groundless.”
Two days ago, Russian Foreign Ministry Spokesperson Maria Zakharova slammed the “lies” about election hacking in a statement on the website of Russia’s embassy in the US.
The statement said: “Frankly speaking, we are tired of lies about Russian hackers that continue to be spread in the United States from the very top.
“The Obama administration launched this misinformation half a year ago in a bid to play up to the required nominee at the November presidential election and, having failed to achieve the desired effect, has been trying to justify its failure by taking it out with a vengeance on Russian-US relations.”