Maybe it should be a verb: To be Guccifered. Though maybe, in Hillary Clinton’s case, it would be better phrased as a crime. As in: “They got her on a Guccifer.”

Guccifer is the nom de Internet of the Romanian hacker Marcel Lehel Lazar. Few people realize it, but the Eastern European anti-hero is why the world knows that Hillary Clinton maintained a private email server while secretary of state. This week he may have made Mrs. Clinton’s road to the White House a lot rougher.

It’s a case study in why governments have rules about online security. Guccifer’s specialty was hacking top officials and their relatives—with an eye toward mayhem and humiliation. He hacked the account of Dorothy Bush Koch and circulated photos of her father, former President George H.W. Bush, in the hospital. He hacked years of Colin Powell’s correspondence, including personal financial information. He went after FBI and Secret Service agents, senators and the wealthy.

In March of 2013, Guccifer released hacked AOL email correspondence of Clinton crony Sidney Blumenthal, revealing numerous memos he’d sent to Hillary while she was the nation’s top diplomat. Mr. Blumenthal had sent these notes to Mrs. Clinton at a private, nongovernmental email address. Security experts tut-tutted about the risks, though the assumption was that Mrs. Clinton used the private account for the occasional interaction with friends or political operatives. It wasn’t until early 2015 that the nation found out Hillary was using the home-brew server to conduct every bit of her state business.

But that timing is by the by. What matters is that Guccifer knew, at least by March of 2013, that the third-highest official in the executive branch of the most powerful nation of the world was using a private server. Does anyone think a man devoted to hacking politicians and Federal Reserve bankers would ignore that opportunity?