The hacker or hacking group is known by the nickname Fancy Bear, and is alleged to be working for the Russian government. Fancy Bear gets into the DNC network in April 2016, which makes it separate from the efforts of Cozy Bear (alleged also to be linked to Russia) or Guccifer 2.0 (alleged to be a “lone hacker”) which in either case got into the network for about a year. Fancy Bear’s attack on Clinton’s staffers is said to start in March 2016, according to the security firm SecureWorks. Targets include Clinton’s communications and travel organizers, speechwriters, policy advisers, and campaign finance managers.
The hackers use the “spear phishing” technique of sending an email from a seemingly trusted source in order to get the target to click on a link. In this case, the links are shortened by an Internet service known as Bitly to make it hard to notice that they’re bogus. They take the target to a fake Google login page, since most or all of Clinton’s staffers use Gmail. Once the target gives their user name and password, the hacker can log into the real account and access all the data. The hackers create 213 links targeting 108 hillaryclinton.com addresses. Twenty of those are clicked, raising the possibility that some accounts are successfully breached. (Forbes, 6/16/2016)