Justin Harvey, a cybersecurity expert who works at Accenture, one of the firms that helped investigate the hack, told ABC News in July that there were two actors involved in the attack on the DNC. 

“One of them is Russian intelligence and one of them is the Russian military,” Harvey said. “We saw the Cyrillic alphabet being use in the compiler, we saw the level of complexity of the malware is not your run-of-the-mail ransomware cybercriminal that perhaps sits in their mother's basement, it was very much nation-state level, very complex code that was being utilized.” 

But, Harvey said, the clearest evidence was the IP address that that malicious software used to phone home. 

“It was an IP address that had been previously seen in other Russian-attributed attacks, including the German parliament, the Bundestag, they encountered a breach last year with the same malware, the same IP address, and then also attributed to the Russians,” he said.