As laid out in the article: It turns out that any device you connect with an iOS via the USB port can obtain your device's Universal Device ID (UDID), as long

As laid out in the article: It turns out that any device you connect with an iOS via the USB port can obtain your device's Universal Device ID (UDID), as long as the device isn't passcode-locked. It just takes a second, so if you plug in your device while it's unlocked, or unlock it while plugged in, or just don't have a passcode, Mactans can attack.