My firewall keeps reporting intrusion attempts described as "DCE endpoint resolution." What's going on? The intrusion even seems to be coming from my own ISP on TCP port 135!
Port 135 is registered as "epmap - DCE endpoint resolution" and can be enumerated by connecting on port 135 and doing the appropriate queries. Mostly used by Microsoft for RPC locator service, it can be used to lookup what ports other services are running on Distributed Computing Environment (DCE) services on the remote host. An attacker may use this fact to gain more knowledge about the remote host. Trojans are a common example that exploits this vulnerability.
The solution: filter incoming traffic to this port. If possible, this port should NOT be opened except in certain circumstances where you are protected by another firewall (e.g. in a corporate DMZ situation).
Dig deeper on Network Security Monitoring and Analysis
Related Q&A from Puneet Mehta
To view network security expert Puneet Mehta's latest advice, see his Public Profile on the IT Knowledge Exchange: http://...continue reading
Find out if there's a difference between a virtual private network (VPN) concentrator and a network access server (NAS) in this explanation from our ...continue reading
Our network security expert explains how to keep unauthorized users from accessing your router's IP address for Internet access in this advice ...continue reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.