According to the International Business Times, Russian cosmonauts brought a removable device into the International Space Station, which infected the space station's systems.
Kaspersky doesn't give any details about when the infection he was told about took place, but it appears as if it was prior to May of this year when the United Space Alliance, the group which oversees the operaiton of the ISS, moved all systems entirely to Linux to make them more "stable and reliable."
Prior to this move the "dozens of laptops" used on board the space station had been using Windows XP, which is inherently more vulnerable to infection from malware than Linux.
According to Kaspersky the infections occurred on laptops used by scientists who used Windows as their main platform and carried USB sticks into space when visiting the ISS.
The ISS's control systems (known generally as SCADA systems) were already running various flavours of Linux prior to this switch for laptops last May.
|When Computer Viruses Infect Worms by Mistake|
|The Binary Low Table: Furniture Made Out of Obsolete Computer Parts|
|Internet Archive Releases Historical Software Collection|
|Classic Clips: Bill Gates Chews Out Microsoft Over XP|
|Tiny Yet Functional Atari 810 Disk Drive|
|AI and Robotic Arms Remove Trash from Recycling|
|“Previously unknown plastic contamination in the tap water of cities around the world.”|
|“He says he tries to use Facebook as little as possible, and that his children aren’t allowed to use that shit.”|
|Ubuntu 17.10 Artful "What the Fuck" Aardvark|
|iotacons: Pixelated Art by Andy Rash|
|“Google is our modern man's God.”|
|“Millions of Americans are hassled to pay back money they don’t owe.”|
|Japanese Robot Serves Ice Cream From Inside a Vending Machine|
|How to Avoid Jury Duty|
|"100 of its members occupied the Opera Apple Store in Paris, demanding the company pay its taxes."|
|“The results of its People You May Know algorithm are anything but obvious.”|
|“End your life with a click.”|