On March 24, 2019, Attorney General Barr released his summary of the Mueller Report. While there has been a lot of coverage of the report, this passage about Russian interference has received little attention in the media:
The second element involved the Russian government’s efforts to conduct computer hacking operations designed to gather and disseminate information to influence the election. The Special Counsel found that Russian government actors successfully hacked into computers and obtained emails from persons affiliated with the Clinton campaign and Democratic Party organizations, and publicly disseminated those materials through various intermediaries, including WikiLeaks. Based on these activities, the Special Counsel brought criminal charges against a number of Russian military officers for conspiring to hack into computers in the United States for purposes of influencing the election. But as noted above, the Special Counsel did not find that the Trump campaign, or anyone associated with it, conspired or coordinated with the Russian government in these efforts, despite multiple offers from Russian-affiliated individuals to assist the Trump campaign.
Hacking means to gain unauthorized access to a computer. We know from the indictments of the Russians that the specific hacking method used by the Russians was spearphishing. Spearphishing works because it is easy to create deceptive emails. SP Guard from Iconix fights email deception.