Apparently those hackers are scouring the emails of left-leaning organizations for embarrassing details and attempting to extract hush money in the form of, drumroll, "evil, anti-establishment" bitcoin. 

At least a dozen groups have faced extortion attempts since the U.S. presidential election, said the people, who provided broad outlines of the campaign. The ransom demands are accompanied by samples of sensitive data in the hackers' possession.
 
In one case, a non-profit group and a prominent liberal donor discussed how to use grant money to cover some costs for anti-Trump protesters. The identities were not disclosed, and it's unclear if the protesters were paid.
 
At least some groups have paid the ransoms even though there is little guarantee the documents won't be made public anyway. Demands have ranged from about $30,000 to $150,000, payable in untraceable bitcoins, according to one of the people familiar with the probe.

Of course, in what has become a journalistic norm, all of the details from Bloomberg come from two anonymous people "familiar with probes being conducted by the FBI and private security firms."