The volume of known ransomware attacks surged last month to record-breaking levels, security researchers report.

Ransomware groups collectively listed 514 victims on their data-leak sites in September, breaking the previous record in July of 502 victims, said U.K. cybersecurity firm NCC Group. The firm reports that “major drivers of this activity” include newer groups such as LostTrust, Cactus, and RansomedVC.

LostTrust listed 53 victims in September, accounting for 10% of listed attacks, placing it second only to LockBit, which counted 72 victims, cybersecurity firm Malwarebytes reported. Cactus and RansomedVC each listed 33 victims in September, it said, with RansomedVC notching up an especially high-profile victim in the form of Sony.