German multinational building and construction material provider Knauf Group has been impacted by a cyberattack late last month, which has been claimed by the Black Basta ransomware gang, BleepingComputer reports. Attackers hit Knauf on June 29, prompting the firm to shut down its email systems as it works on incident response and remediation efforts. "We are currently working heavily to mitigate the impact to our customers and partners as well as to plan a safe recovery. However, we apologize for any inconvenience or delays in our delivery processes, that may occur," said Knauf. Knauf did not provide more details about the attack but the Black Basta ransomware group took responsibility for the intrusion, posting the company as a victim on Saturday and leaking 20% of allegedly exfiltrated files. Included in the exposed files, which have already been accessed by 350 visitors, were email communications, employee contact details, user credentials, ID scans, and production files.