Aleksey Lukashev was one of the 12 Russian intelligence officers indicted by the special counsel in July of 2018.
Spearphishing is an upgraded form of Phishing, it involves sending a spoof email but the email is geared toward a specific individual and appears to be from someone they know, often a superior, so the target will open the email. The message will seem important, if not vital, and ask the target to click something that secretly installs malware, or tells them to go to a specific url where they’ll be tricked into exposing their password.
Once the documents were obtained by Unit 26165, they were posted online and given to WikiLeaks using the personas Guccifer 2.0 and DNCLeaks.
The constitution of Russia doesn’t allow extradition, so it’s unlikely any of the officers will be brought to justice.