That is according to new research published on August 14 by digital rights groups Citizen Lab and Access Now, Ukrinform reports, citing Reuters.
The phishing campaign is part of a sweeping internet espionage operation, the researchers say, and comes as U.S. officials are closely monitoring computer networks to thwart any cyberattacks against the 2024 presidential election.
The email hacks began around 2022 and have targeted prominent Russian opposition figures-in-exile, former U.S. think tank and policy officials and academics, U.S. and EU nonprofit staff, as well as media organizations, the report said.
Some of those targeted were still in Russia, "placing them at considerable risk", the researchers said, adding that the victims may have been selected to try to gain access to their extensive networks of contacts.
Citizen Lab attributed the hacking to two groups: the prominent Russian hacking outfit Cold River, which Western intelligence and security officials have linked to Russia's Federal Security Service (FSB), and a new group dubbed Coldwastrel, which appeared to support Russian intelligence.
Russia has consistently denied allegations of hacking during past incidents linked to Cold River.
One of the victims of the hacking operation was a former U.S. ambassador to Ukraine, who was targeted with a "credible effort" impersonating a fellow former ambassador known to him, according to the report, which did not name the person.
