He took detailed notes about what he saw through his spying and kept millions of the images he gained access to through Fruitfly.
The federal indictment says Durachinsky recorded minors having sex over a five-year period. Security firm Malwarebytes a year ago also found that the malware had infected biomedical research institutions.
Authorities believe Durachinsky developed Fruitfly, a Mac spyware strain that has been active since 2003 and has infected thousands of computers.
Last July, Patrick Wardle, a researcher specializing in Mac malware at security firm Synack, found a new version of Fruitfly.
The indictment said that Durachinsky accessed thousands of computers, including ones owned by schools, a police department and a subsidiary of the US Department of Energy.More news: Saints beat Panthers, confident about rematch with Vikings
Forbes also reported that Durachinsky was charged in a separate criminal complaint filed in January 2017 that accused him of hacking computers at Case Western Reserve University in Cleveland, Ohio. In a finding that proved prescient, about 20 percent of the infected machines were in Ohio. In some cases, Fruitfly alerted Durachinsky when victims typed words associated with porn.
The FruitFly malware was also the subject of a presentation at the Black Hat USA 2017 and DEF CON 2017 security conferences.
Wardle concluded that Fruitfly "was created by a hacker or some malware author to basically spy on victims for perverse reasons, which kind of sucks".
Within this week's complaint, prosecutors also asked the court to order that Durachinsky forfeit any property he derived from his 13-year campaign, an indication that they allege he sold the images and data he acquired to others.
He allegedly used his creation to turn on thousands of infected systems' microphones and webcams, capture images, log keystrokes, and steal tax and medical records, photographs, Internet searches, and bank transactions.More news: Justin Bieber & Selena Gomez Apart on Christmas, But Together for New Year's
It's still unclear how Fruitfly ended up on computers.
"Durachinsky is further alleged to have watched and listened to victims without their knowledge or permission and intercepted oral communications taking place in the room where the infected computer was located", the Justice Department wrote.
To store the information and obscure the activity, Fruitfly needed bandwidth and storage.
Durachinsky's software was working in Macs whose owners were insisting that they were using an operating system which was more secure by design.
"Defendant used certain Fruitfly victims' computer networks to access sufficient bandwidth to allow the Fruitfly malware to infected protected computers", not only in OH but worldwide, the indictment reads.More news: Joe Arpaio announces he's running for Senate
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