Seyfarth Shaw is the latest Big Law firm to get hit by a cyberattack. The firm said in a statement Monday morning that it was victimized by “a sophisticated and aggressive malware attack that appears to be ransomware” over the weekend.

The Am Law 100 firm added that there’s not yet any reason to think client data was stolen or removed in the Saturday attack, but that it is still working to bring its systems back online.