Hyland OnBase contains an unauthenticated .NET Remoting exposure in the OnBase Workflow Timer Service (Hyland.Core.Workflow.NTService.exe) and is also reported by the vendor to impact the Workview Timer Service (an impacted version range is undefined). An attacker who can reach the service can send crafted .NET Remoting requests to default HTTP channel endpoints on TCP/8900 (e.g., TimerServiceAPI.rem and TimerServiceEvents.rem for Workflow) to trigger unsafe object unmarshalling, enabling arbitrary file read/write. By writing attacker-controlled content into web-accessible locations or chaining with other OnBase features, this can lead to remote code execution. The same primitive can be abused by supplying a UNC path to coerce outbound NTLM authentication (SMB coercion) to an attacker-controlled host.
It is recommended that customers immediately convert to the in-servicing module, Unity Scheduler, and uninstall the Workflow Timer Service (Hyland.Core.Workflow.NTService.exe). Starting with OnBase 16, Unity Scheduler is the recommended replacement. It is recommended customers using versions prior to 16 upgrade to an in-servicing release of OnBase and leverage Unity Scheduler.