Penetration Testing mailing list archives
Re: Tool to find hidden web proxy server
From: Jose Maria Lopez <jkerouac () bgsec com>
Date: 03 Sep 2004 19:20:10 +0200
El vie, 03 de 09 de 2004 a las 02:04, Gary E. Miller escribió:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Yo Jose! On Thu, 2 Sep 2004, Jose Maria Lopez wrote:But if you allow in and out from specific ports you have at least a second level of security over what the original poster said it had. Only allowing out from some IPs it's possible, but I find it very difficult to make rules for the outer IPs, having in mind the original poster wants to have internet connection from the LAN for that machines.If you leave just ONE port open, then an insider can use it to tunnel out. That one port is often DNS/udp. You have to work very, very, hard to filter out IP over DNS/udp. You could force the use of an internal DNS server, but if it allows any recursive lookups out of the firewall then game over. This /. describes how to do it: http://slashdot.org/articles/00/09/10/2230242.shtml The insider does not even need an open port. Only TCP/IP (proto 6) and TCP/UDP (proto 17) use "ports". The insider can just use a "portless" protocol like TCP/ICMP (proto 1), TCP/ESP (proto 50), TCP/AH (proto 51), etc. There are several IPSEC stacks available as freeware that use TCP/ESP and TCP/AH. RGDS GARY - --------------------------------------------------------------------------- Gary E. Miller Rellim 20340 Empire Blvd, Suite E-3, Bend, OR 97701 gem () rellim com Tel:+1(541)382-8588 Fax: +1(541)382-8676 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.3 (GNU/Linux) iD8DBQFBN7T48KZibdeR3qURAm4gAJ9GXYH6eeVS55+ai8SLOT93raeBKACg2BGf QUxTOF4ZbKCUlGm33D2r0+w= =HiIK -----END PGP SIGNATURE-----
I agree completely. And finding a firewall piercing through ICMP packets for example can be quite tricky, and I have some tools that can proxy traffic through a firewall with ICMP packets. The other protocols are less dangerous, I think. If you don't need them you just block them at the firewall, if you need them you just permit the traffic between the VPN devices and not route all the traffic through them. I think TREX can do some kind of application firewall for DNS, HTTP and all the common services one wants to open at the firewall. But it's so hard to compile it that I couldn't try it yet, but it could solve the problem. -- Jose Maria Lopez Hernandez Director Tecnico de bgSEC jkerouac () bgsec com bgSEC Seguridad y Consultoria de Sistemas Informaticos http://www.bgsec.com ESPAÑA The only people for me are the mad ones -- the ones who are mad to live, mad to talk, mad to be saved, desirous of everything at the same time, the ones who never yawn or say a commonplace thing, but burn, burn, burn like fabulous yellow Roman candles. -- Jack Kerouac, "On the Road" ------------------------------------------------------------------------------ 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:
- Re: Tool to find hidden web proxy server, (continued)
- Re: Tool to find hidden web proxy server vinay mangal (Sep 01)
- Re: Tool to find hidden web proxy server Javier Fernandez-Sanguino (Sep 02)
- Re: Tool to find hidden web proxy server Marc (Sep 02)
- Re: Tool to find hidden web proxy server Martin Mačok (Sep 02)
- Re: Tool to find hidden web proxy server Christine Kronberg (Sep 02)
- Re: Tool to find hidden web proxy server Paulo Henrique Fisch de Brito (Sep 02)
- Re: Tool to find hidden web proxy server Jose Maria Lopez (Sep 02)
- Re: Tool to find hidden web proxy server R. DuFresne (Sep 02)
- Re: Tool to find hidden web proxy server Jose Maria Lopez (Sep 02)
- Re: Tool to find hidden web proxy server Gary E. Miller (Sep 03)
- Re: Tool to find hidden web proxy server Jose Maria Lopez (Sep 03)
- Re: Tool to find hidden web proxy server vinay mangal (Sep 01)
- Re: Tool to find hidden web proxy server Chris Brenton (Sep 02)
- Re: Tool to find hidden web proxy server Gary E. Miller (Sep 02)
- Re: Tool to find hidden web proxy server hashem (Sep 02)
- Re: Tool to find hidden web proxy server Rogan Dawes (Sep 02)
- Re: Tool to find hidden web proxy server Thor (Sep 03)
- RE: Tool to find hidden web proxy server Aditya Deshmukh (Sep 03)
- Re: Tool to find hidden web proxy server Balaji Prasad (Sep 05)
- Re: Tool to find hidden web proxy server Jose Maria Lopez (Sep 08)