International law firm Jones Day has been targeted in a ransomware attack and the stolen files were dumped on the internet.

The attack is believed to have involved the Clop ransomware gang, the same group behind an attack on German tech giant Software AG in October. Officially Jones Day is claiming that its network was not compromised and that the theft of data involved a file-sharing company that it uses to store files.

Those behind the Clop ransomware argue otherwise, claiming that they had obtained 100 gigabytes of files from servers belonging to Jones Day and have started to publish redacted files as proof of their successful ransomware attack demanding 20$ million dollars

The attack vector was via a vulnerability in software from Accellion Inc., a Palo Alto-based private cloud solutions company focused on secure file sharing and collaboration.

Even if how files were stolen from Jones Day could be arguable given the law firm’s seeming lack of solid confirmation, data was indeed stolen. The Wall Street Journal reported today that it not only could view some files but also could “see the existence of many more files mammoth in size also purported to belong to Jones Day.”