U.S. authorities have demanded a nearly eight-year prison sentence for a Kazakh-born computer hacker, asserting that a harsh term would send a message to Russia's main intelligence agency about hacking and espionage.
Federal prosecutors made the arguments in court filings in San Francisco ahead of the next hearing for Karim Baratov, who is scheduled to be sentenced on April 24.
The U.S. prosecution against Baratov has yielded glimpses into how Russian intelligence agencies -- the Federal Security Service (FSB), first and foremost -- may use computer hackers in the theft of passwords, e-mails, and espionage.
Baratov, who was born in Kazakhstan and was living in Canada at the time of his arrest, pleaded guilty to charges that he helped hack into Yahoo, affecting hundreds of millions of accounts in what has turned into the largest data breach in history.
As part of his plea deal, Baratov agreed to cooperate with U.S. prosecutors in their investigation of the Yahoo hack. Two officers from the FSB have also been charged, along with another Russian hacker on the FBI's most wanted list.
In the filings in San Francisco's U.S. federal court, prosecutors argued that Baratov had agreed to hack into Yahoo's servers sometime between January 2014 and December 2016 as part of a conspiracy overseen by FSB officers.
Baratov, for his part, said he did not know the identities of the people who hired him to hack.
One of the two FSB officers identified in court papers is Dmitry Dokuchayev, who worked in the FSB's Center for Information Security, the agency's lead cyberunit.
In December 2016, four months before the U.S. indictments were released, Dokuchayev and his superior, Sergei Mikhailov, were arrested in Moscow and charged with treason along with a researcher for the private computer company Kaspersky Lab.
The head of the Center for Information Security -- a senior veteran FSB officer -- was later reportedly forced into retirement.
The timing of the arrests, along with the seriousness of the charges, has fueled intense speculation among cyberresearchers and experts on Russian intelligence agencies.
The FSB, along with Russia's military intelligence agency, the GRU, have both been blamed for hacking campaigns that targeted U.S. political operatives, including the Democratic National Committee.
In their San Francisco court filings, prosecutors asserted that a long prison sentence for Baratov would serve as a message to the FSB.
"The fact that Defendant Baratov was hired and agreed to hack webmail accounts for an officer of the Russian FSB...underscores the need for a significant and strong message of deterrence," they wrote.
"For cybercriminals like the defendant, there must be a significant sentence of imprisonment that accounts for hacking in such a prolific and indifferent manner that one is hired as a proxy for the Russian FSB," U.S. authorities said.
Since the arrest in Moscow, little has been made public about the progress of the treason case against Dokuchayev, Mikhailov, and the others that have been charged. Defense lawyers involved in the case have also complained about a lack of information.
But leaks to Russian newspapers have pointed to the possibility that the FSB officers were being targeted due to earlier cooperation with U.S. and other intelligence and law enforcement agencies in pursuing Russian hackers.
Earlier this month, the Russian newspaper RBC quoted an unnamed security source as saying that Dokuchayev and another man, Georgy Fomchenkov, had entered a partial guilty plea to "passing evidence to foreign security services in an informal manner."
Mikhailov, the newspaper said, was maintaining his innocence, as was Kaspersky Lab researcher Ruslan Stoyanov.