Law enforcement officials in more than a dozen countries arrested scores of individuals as part of a U.S. Federal Bureau of Investigation crackdown on the makers and purveyors of malicious computer software called the Blackshades Remote Access tool.

The government unsealed charges against five people, including Alex Yucel, alleged to be the owner and operator of the Blackshades website and creator of the malware, which allowed users to secretly gain access to victims’ computers. The remote access tool, or RAT, gives users access to computer files and allows them to steal passwords and even activate victims’ web cameras to spy on them, according to the charges.

The Blackshades RAT was purchased by at least several thousand users in more than 100 countries, according to a criminal complaint. The RAT was used to infect more than 500,000 computers worldwide, according to the government.

Yucel is charged with five crimes, including conspiracy, distribution of malicious software, access device fraud and aggravated identity theft. He was arrested in Moldova in November 2013, according to Jerika Richardson, a spokeswoman for U.S. Attorney Preet Bharara in Manhattan. He remains in custody there awaiting extradition.

Bharara has scheduled a press conference for later today.