Port 60899 — The Unassigned Port and the Downloader

What Port 60899 Is

Port 60899 is unassigned. It belongs to the dynamic and private port range (49152-65535), which means IANA never allocated it to any specific service. ¹ Ports in this range exist for temporary use: ephemeral connections that your operating system assigns on the fly, custom applications that need a listening port, and services that want to operate without official registration.

This is intentional design. The port range reserves space for the unmapped, the experimental, the private. Most of the time, that's exactly what it's used for—temporary traffic that nobody cares about, lost within seconds.

The Malware Connection

Port 60899 became notable for hosting something much less temporary.

Trojan.DownLoader34.3753 uses this port (along with others in the 60800-60900 range) for command and control operations. ² The malware:

• Injects code into system processes like svchost.exe and iexplore.exe
• Creates Tor-based infrastructure for botnet communications
• Modifies the file system and deploys supporting files like opencl.dll
• Listens on this port for commands from its operators

This is a sophisticated threat—documented since at least July 2020—that chose to operate in the unassigned space. No registry entry to trace. No official service name to search for. Just a port number in the darkness.

How to Check What's Listening

If you need to investigate activity on this port, you have a few tools:

On macOS/Linux:

lsof -i :60899
netstat -tlnp | grep 60899

On Windows:

netstat -ano | findstr :60899
Get-NetTCPConnection -LocalPort 60899 | Select-Object OwningProcess, ProcessName

Across platforms:

telnet localhost 60899
nc -zv localhost 60899

If something is listening, check the process name against your expected applications. If you don't recognize it—and especially if it's making outbound connections—that's a sign to investigate further. Malware often hides in the dynamic range because nobody's watching it.

Why Unassigned Ports Matter

The dynamic range (49152-65535) contains 16,384 ports. That's a lot of darkness. Official services register their ports so administrators can easily recognize them. A listening socket on port 22 immediately registers as SSH. Port 443 means HTTPS.

But port 60899? No alarm bells. No automatic recognition. That's the point—and that's the problem.

Malware, rogue services, and legitimate custom applications all live here. The system can't distinguish between them automatically. A listening port on 60899 could be:

• A legitimate internal application
• An ephemeral connection you can ignore in seconds
• A trojan waiting for commands

You have to look. That's the tax of the unassigned range—no help from standards, no easy answers. Just you, a port number, and whatever's listening on it.