Microsoft says Russian attempts to launch cyber-attacks against US conservative groups have been thwarted.
The software company said Russian hackers had tried to steal data from political organisations, including the International Republican Institute and the Hudson Institute think tanks.
But they had been thwarted when its security staff won control of six net domains mimicking their websites.
Microsoft said the Fancy Bear hacking group had been behind the attacks.
Microsoft said the thwarted attack was likely the start of a “spear phishing” campaign that is intended to trick people into visiting the mimicked domains allowing the Fancy Bear group to see and steal login information that people use.
As well as the two think-tanks, the domains seized were associated with several Senate offices and services. One domain sought to mimic Microsoft’s Office 365 online service.
Microsoft’s action comes soon after the US charged 12 Russian intelligence officers with hacking computer networks used by Hillary Clinton and the Democratic Party.
Russia has consistently denied meddling in the elections or mounting any cyber-attacks on US institutions.