When using an object storage like S3 as the file store, when a user creates a public link to a folder where anonymous users can upload files, and another user uploads a virus the files antivirus app would detect the virus but fails to delete it due to permission issues. This affects the filesantivirus component versions before 0.15.2 for ownCloud.
The filesantivirus component before 1.0.0 for ownCloud mishandles the protection mechanism by which malicious files (that have been uploaded to a public share) are supposed to be deleted upon detection.
The filesantivirus component before 1.0.0 for ownCloud allows OS Command Injection via the administration settings.