A new ransomware gang called Black Basta has claimed responsibility for the attack on the American Dental Association. The attackers claimed to have leaked 2.8GB of data, which they believe accounts for about 30% of the stolen data from the attack.

Following the claims published on the Black Basta ransomware leak site, the attackers proceeded to leak data allegedly stolen during the attack, according to security expert MalwareHunterTeam.

The American Dental Association (ADA) suffered a ransomware attack on Friday that forced it to take parts of its network offline.

The outage has made some of their online services inaccessible, including the ADA Store, the ADA Catalog, My ADA, Meeting Registration, Dues pages, ADA CE Online, the ADA Credentialing Service and the ADA Practice Transitions.

In the email to members, ADA said it was working with “third-party cybersecurity specialists” and law enforcement agencies to investigate the attack. The association stated that preliminary investigations did not indicate that members’ information or other data were compromised during the attack.

ADA members are advised to be on the lookout for targeted spear-phishing emails that could attempt to steal their credentials.