A man portrayed as a ringleader in an international cyber scam has pleaded guilty.
Vladimir Tsastsin, an Estonian citizen, entered the plea on Wednesday in a Manhattan federal court.
The plea related to a scheme that, authorities said, infected more than four million computers in more than 100 countries with software that disabled anti-virus protections and steered users to websites they did not choose.
Sentencing was set for October 14.
Prosecutors say more than a half a million computers were infected in the United States, including computers belonging to government agencies such as NASA.
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Prosecutors say infected computers also belonged to educational institutions, non-profit organisations, commercial businesses and individuals.
They said Tsastsin and co-conspirators profited by receiving payments for higher internet traffic after they digitally hijacked internet searches and rerouted computers to certain websites and advertisements.
