Warner questions health care groups on cybersecurity
Russian hackers targeted McCaskill's office
The news site reported that McCaskill, considered among the most vulnerable senators up for reelection, was one of three congressional candidates a Microsoft executive said last week had been targeted by hackers.
"Russia continues to engage in cyber warfare against our democracy," McCaskill said in a statement. "I will continue to speak out and press to hold them accountable. While this attack was not successful, it is outrageous that they think they can get away with this. I will not be intimidated. I've said it before and I will say it again, Putin is a thug and a bully."
The report comes shortly after special counsel Robert Mueller indicted 12 Russian intelligence officers in the hacking of the Democratic National Committee in 2016, the latest charges filed in his ongoing probe of Moscow's election interference.
McCaskill, whose home state of Missouri went to President Trump by double-digits, would be the first confirmed target of attempted Russian hacking in the 2018 midterms.
The Daily Beast reported that the hackers targeted Senate staffers through phishing emails, falsely telling them that their Microsoft Exchange passwords had expired and sending them to a mock-up of the Senate's Active Directory Federation Services login page.
Microsoft seized one of the fake sites in October and redirected traffic from the domain to its own server. This allowed the company to see who was sent to the mock site.
"Earlier this year, we did discover that a fake Microsoft domain had been established as the landing page for phishing attacks," Tom Burt, Microsoft's vice president for security and trust, said at the Aspen Security Forum last week.
Burt said that Microsoft had blocked the attempted breaches, and the Daily Beast reported that the attempts against McCaskill's team were ultimately unsuccessful.
Tokyo-based cybersecurity group Trend Micro told The Hill earlier this year that it had identified websites designed to look like the U.S. Senate's internal email system and that they were part of an email-harvesting operation.
The sites were reportedly created by the Russian hacking group known as "Fancy Bear," which is linked to the 2016 DNC hack. The Daily Beast reported that the techniques used by the Fancy Bear hackers were similar to those used on McCaskill's staff.
The Daily Beast noted that the attempted breach against McCaskill took place in August 2017, around the time Trump took a trip to Missouri, where he urged attendees at a rally to vote McCaskill out of office.
"We must lower our taxes and your senator, Claire McCaskill, she must do this for you, and if she doesn't, you have to vote her out of office," Trump said at the time.
Last week, amid fierce criticism of his friendly press conference with Russian President Vladimir Putin, Trump tweeted that Russia might interfere in the upcoming midterm elections to help Democratic candidates.
Speaking next to Trump in Finland, Putin said that he had hoped the president would beat Democratic nominee Hillary Clinton in 2016.
"Yes, I did, because he was the one who wanted to normalize relations with Russia," Putin said when asked if he wanted Trump to win.
- Updated at 10:17 p.m.