Security Basics mailing list archives
RE: Scanning--more then one side to the argument
From: "Steve Fletcher" <safletcher () insightbb com>
Date: Thu, 31 Mar 2005 00:36:41 -0600
Yes, I would consider the open ports an issue. I won't disagree with that. However, I'm curious why those ports are showing as open when the others are filtered. Are you firewalling some ports, but not all? One thing, too. You might want to upgrade to a newer version of nmap. Version 3.81 has been out for a little while. There have been a number of improvements since 3.50. I'm not sure if it would affect your results, but it's possible. Steve -----Original Message----- From: Shand [mailto:shand () adelphia net] Sent: Wednesday, March 30, 2005 3:17 PM To: Steve Fletcher; security-basics () securityfocus com Subject: Re: Scanning--more then one side to the argument Example of customer scan nmap -sV -P0 -p 1- Starting nmap 3.50 ( http://www.insecure.org/nmap/ ) at 2005-03-30 16:59 EST Interesting ports on (The 65522 ports scanned but not shown below are in state: closed) PORT STATE SERVICE VERSION 80/tcp filtered http 135/tcp filtered msrpc 136/tcp filtered profile 137/tcp filtered netbios-ns 138/tcp filtered netbios-dgm 139/tcp filtered netbios-ssn 445/tcp filtered microsoft-ds 5000/tcp open upnp Microsoft Windows UPnP 5241/tcp open unknown 7177/tcp open unknown 8031/tcp open unknown 9491/tcp open unknown 27374/tcp filtered subseven Nmap run completed -- 1 IP address (1 host up) scanned in 438.716 seconds Now I see this as a issue? Other don't? The filtered ones are filtered by us. The others they have open? ( Not firewall?) ( No security?) Sherman ----- Original Message ----- From: "Steve Fletcher" <safletcher () insightbb com> To: "'Shand'" <shand () adelphia net>; <security-basics () securityfocus com> Sent: Wednesday, March 30, 2005 3:41 PM Subject: RE: Scanning--more then one side to the argument
That would depend on the port and what function it serves. For example, you might show port 25 as open because they have an SMTP server and it is not behind a firewall. Here is a definition of the different states, straight from the nmap man page: "The state is either "open", "filtered", or "unfiltered". Open means that the target machine will accept() connections on that port. Filtered means that a firewall, filter, or other network obstacle is covering the port and preventing nmap from determining whether the port is open. Unfiltered means that the port is known by nmap to be closed and no firewall/filter seems to be interfering with nmap's attempts to determine this. Unfiltered ports are the common case and are only shown when most of the scanned ports are in the filtered state." Hope this helps. Steve Fletcher MCSE (NT4/Win2k), MCSE: Security (Win2k), HP Master ASE, CCNA, Security+ safletcher () insightbb com -----Original Message----- From: Shand [mailto:shand () adelphia net] Sent: Wednesday, March 30, 2005 2:33 PM To: Steve Fletcher; security-basics () securityfocus com Subject: Re: Scanning--more then one side to the argument External scans. Against customer using our internet service. Does a port have to show as "open" or can they for usability show only as filtered, closed? Thoughts? Shand ----- Original Message ----- From: "Steve Fletcher" <safletcher () insightbb com> To: "'Sherman Hand'" <shand () adelphia net>; <security-basics () securityfocus com> Sent: Wednesday, March 30, 2005 3:18 PM Subject: RE: Scanning--more then one side to the argumentI have a question regarding this. Are you talking about doing an external scan or an internal scan? I assume an external, because an internal scan should show a LOT of open ports. I would say that any open port POTENTIALLY could be a security issue waiting to happen, but common sense dictates that some ports must be open for usability reasons. Plus, if you're going to follow this line of thought, the fact that the systems are connected to the Internet AT ALL poses a potential risk. Or, just being networked could be a risk. Or, being powered on poses a potential risk. So, based on this, sure it COULD be a security risk waiting to happen, but more information needs to be gathered to determine the true extent of the risk. And, it must be reevaluated at regular intervals to catch new issues that might have come up since the last scan. What is safe now might not be 6 months from now. Hope this helps. Steve Fletcher MCSE (NT4/Win2k), MCSE: Security (Win2k), HP Master ASE, CCNA, Security+ safletcher () insightbb com -----Original Message----- From: Sherman Hand [mailto:shand () adelphia net] Sent: Wednesday, March 30, 2005 5:05 PM To: security-basics () securityfocus com Subject: Scanning--more then one side to the argument There has been a on going discussion about the scanning results on our customers. Thought one says that "any" port on a standard nmap, showing as "open" is a security risk. Thought two says, no since some things need to show in a state of open. Should we be stating that through proactive scan, when we find any port showing as open, that it is a security issue waiting to happen? Or only if we can show a issue? Thoughts? Shand
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Current thread:
- Scanning--more then one side to the argument Sherman Hand (Mar 30)
- Re: Scanning--more then one side to the argument Barrie Dempster (Mar 31)
- RE: Scanning--more then one side to the argument Steve Fletcher (Mar 31)
- <Possible follow-ups>
- Re: Scanning--more then one side to the argument Shand (Mar 31)
- RE: Scanning--more then one side to the argument Steve Fletcher (Mar 31)
- Re: Scanning--more then one side to the argument Shand (Mar 31)
- RE: Scanning--more then one side to the argument Steve Fletcher (Mar 31)