Penetration Testing mailing list archives
Re: All tcp ports open?
From: Tim <tim-pentest () sentinelchicken org>
Date: Sun, 29 Aug 2004 13:42:45 -0400
I am not sure what is doing this, but I assume it is a software (or some kind of) firewall/hids, can anybody point me in the right direction? I am pen-testing a Windows webserver, and a port scan reveals ALL tcp ports open. hping also confirms that a SA is returned for any S packets sent to any port I try. I can connect via netcat any of the ports, and send data, but nothing is returned. In order to verify services, I am required to connect and check for a banner or send appropriate protocol commands to elicit a response. Has anyone seen this, or have any idea of what this is?
I have seen some load balancers behave this way, but it could also be a firewall responding with SYN/ACK on blocked ports to make it harder for an attacker to see what is open. (The book "Hacking: The Art of Exploitation" by Jon Erickson describes a strategy like this, though I am sure there are many other papers that do as well.) Are you scanning with a SYN scan, or a full connect()? When you connect to a port that you are pretty sure should be closed, does the host ACK your data that you send once the connection is established? If not, then it is probably just a sneaky FW configuration. Have you tried other scans (FIN, ACK, Xmas, etc)? tim ------------------------------------------------------------------------------ Ethical Hacking at the InfoSec Institute. All of our class sizes are guaranteed to be 12 students or less to facilitate one-on-one interaction with one of our expert instructors. Check out our Advanced Hacking course, learn to write exploits and attack security infrastructure. Attend a course taught by an expert instructor with years of in-the-field pen testing experience in our state of the art hacking lab. Master the skills of an Ethical Hacker to better assess the security of your organization. http://www.infosecinstitute.com/courses/ethical_hacking_training.html -------------------------------------------------------------------------------
Current thread:
- All tcp ports open? Ben Timby (Aug 29)
- RE: All tcp ports open? Massimo Cetra (Aug 29)
- Re: All tcp ports open? Andres Riancho (Aug 29)
- Re: All tcp ports open? Bill Burge (Aug 29)
- Re: All tcp ports open? dreamwvr () dreamwvr com (Aug 29)
- Re: All tcp ports open? Tim (Aug 29)
- Re: All tcp ports open? Kevin Sheldrake (Aug 29)
- Re: All tcp ports open? Jose Maria Lopez (Aug 29)
- Re: All tcp ports open? Varun Pitale (Aug 29)
- RE: All tcp ports open? Mike Sues (Aug 30)
- Re: All tcp ports open? Jack Burton (Aug 30)
- Re: All tcp ports open? GUsh-T (Aug 30)
- Re: All tcp ports open? Chris Brenton (Aug 30)
- Re: All tcp ports open? Nathan R. Valentine (Aug 30)
- Re: All tcp ports open? sol seclists (Aug 30)
- <Possible follow-ups>
- RE: All tcp ports open? Don Parker (Aug 29)
(Thread continues...)
- RE: All tcp ports open? Massimo Cetra (Aug 29)