On Wednesday, an individual going by the handle Guccifer 2.0 claimed credit for the hacking of the Democratic National Committee’s network, though a cybersecurity firm investigating the breach stood by its conclusion that Russia was behind the breach.

“Guccifer 2.0” posted to a website some of the allegedly stolen documents. They included a file titled “Donald Trump Report,” dated Dec. 19, 2015, and a list of what was purported to be million-dollar-plus donors to the Democratic Party.

The DNC acknowledged the intrusion Tuesday.

And CrowdStrike, the firm that investigated the breach, said Wednesday that it had no reason to change its assessment.

“CrowdStrike stands fully by its analysis and findings identifying two separate Russian intelligence-affiliated adversaries present in the DNC network in May 2016,” said Dmitri Alperovitch, co-founder and chief technology officer of CrowdStrike.

Alperovitch suggested that the posting may be part of a “Russian disinformation” campaign.

“We are exploring the documents’ authenticity and origin,” he said. “Regardless, these claims do nothing to lessen our findings relating to the Russian government’s involvement, portions of which we have documented for the public and the greater security community.”

The moniker Guccifer 2.0 is an apparent reference to Guccifer, the nom de guerre of a Romanian hacker who is in jail awaiting prosecution in the Eastern District of Virginia for a series of high-profile intrusions. His targets included former secretary of state Colin Powell and family members of former president George W. Bush.