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Windows IP Helper service listening on port 1000

Çağlar Arlı      -    6 Views

Windows IP Helper service listening on port 1000

On a Windows 10 Home machine (21H2 19044.1741), I noticed one of my applications failed to listen on port 1000, because something was already using that port. That struck me as peculiar, because I wasn't familiar with any applications that use 1000 by default.

I ran netstat -ano to get the PID of the process using port 1000.

netstat -ano

That yielded the following process in my Task Manager...

Service Host IP Helper, PID 5784

I turned to google to investigate the Windows IP Helper, but was unable to find results that mention this specific port.

If I run nmap against the machine using nmap -v -p1000 -Pn I receive the following results...

cadlock service, resulting from nmap scan

Perhaps I'm not looking in the right places, but I'm unable to turn up search results for what cadlock is either.

I was able to Stop the IP Helper service from the Services menu, which did indeed free up the port. This behavior persists restarting the computer.

My questions are:

  • Why is this service bound to this port on my machine? I've been unable to recreate this issue in a virtual machine or other bare-metal Windows machines.
  • Could this be malware?
  • How can I investigate this issue further?

Thank you.