Internet-Security.com TCP port 33389 details

TCP 33389 is commonly seen as an alternate port for Microsoft Remote Desktop Protocol (RDP) when administrators change the default 3389 on Windows Remote Desktop Services (e.g., Windows Server 2016/2019/2022).
Linux RDP servers like xrdp are also frequently configured in the wild to listen on 33389 instead of 3389.
Managed service providers and hosting setups often port-forward public 33389 to internal RDP to reduce noise from default-port scans.
Because it’s used as a non-default RDP port, threat actors routinely scan and brute-force 33389; some intrusions relocate RDP to 33389 to evade basic detections, and any RDP vulnerabilities apply regardless of the port.
In short, real-world sightings of 33389 are overwhelmingly RDP services running on a non-standard port.

TCP 33389