Penetration Testing mailing list archives
Re: PIX and ttl
From: "Fabio Pietrosanti (naif)" <naif () sikurezza org>
Date: Fri, 25 May 2001 12:18:00 +0200
On Thu, May 24, 2001 at 07:28:03PM +0100, Fernando Cardoso wrote:
I'm doing a pen-test for a client that has a "standard" config of router-firewall-server_in_dmz. I'm fingerprinting the setup and I'm aware that the firewall is a Cisco PIX (BTW is there any way to change the banner for the fixup protocol smtp? :)
no way, but i think that security configuration of the MTA behind the pix it's thw right way and that "fixup protocol smtp" isn't necessary. It simply add overhead to the Firewall processing...
Their router is at 5 hops of distance from me. Both router and fw gives me the ttl I was expecting when I ping them (251 and 250), but all the servers in the DMZ don't... traceroute to server_in_dmz (x.x.x.x), 30 hops max, 38 byte packets 1 a.a.a.a (a.a.a.a) 2.068 ms 2.031 ms 2.349 ms TTL:255 2 a.a.a.a (a.a.a.a) 153.681 ms 152.925 ms 131.445 ms TTL:254 3 a.a.a.a (a.a.a.a) 205.197 ms 269.539 ms 145.973 ms TTL:253 4 a.a.a.a (a.a.a.a) 38.078 ms 23.849 ms 23.497 ms TTL:252 5 router (router) 31.445 ms 27.277 ms 28.422 ms TTL:251 6 * * * (fw) TTL:250 7 * * * (server_in_dmz) TTL:123 The servers in the DMZ are Microsoft boxes so the "right" TTL should be 122.
No, it's different from release to release of microsoft products... -- Windows NT 4.0 x86 SP6a ( ttl = 128 ) in MY LAN root@life:~# hping -c 2 -S -p 80 10.1.3.20 eth0 default routing interface selected (according to /proc) HPING gongolo (eth0 10.1.3.20): S set, 40 headers + 0 data bytes 46 bytes from 10.1.3.20: flags=SA seq=0 ttl=128 id=25884 win=8576 rtt=0.5 ms -- Windows 2k x86 SP1 ( ttl = 123 ) behind PIX 5.3(1) root@life:~# hping -c 2 -S -p 80 xxx.xxx.xx.xxx eth0 default routing interface selected (according to /proc) HPING www.www.www (eth0 xxx.xxx.xx.xxx): S set, 40 headers + 0 data bytes 46 bytes from xxx.xxx.xx.xxx: flags=SA seq=0 ttl=123 id=10872 win=8576 rtt=27.3 ms -- Windows NT 4.0 x86 unknown SP ( ttl = 118 ) behind 5.3(1) root@life:~# hping -c 1 -S -p 25 xxx.xxx.xxx.xxx eth0 default routing interface selected (according to /proc) HPING xxx.xxx.xxx.xxx (eth0 xxx.xxx.xxx.xxx): S set, 40 headers + 0 data bytes 46 bytes from xxx.xxx.xxx.xxx: flags=SA seq=0 ttl=118 id=45018 win=32768 rtt=860.1 ms -- PIX Itself 5.3(1) ( ttl = 247 ) root@life:~# ping -c 1 xxx.xxx.xxx.x PING xxx.xxx.xxx.x (xxx.xxx.xxx.x): 56 octets data 64 octets from xxx.xxx.xxx.x: icmp_seq=0 ttl=247 time=87.7 ms -- PIX Itself 5.1(4) ( ttl = 251 ) root@life:~# ping -c 1 xxx.xxx.xxx.xx PING xxx.xxx.xxx.x (xxx.xxx.xxx.xx): 56 octets data 64 octets from xxx.xxx.xxx.xx: icmp_seq=0 ttl=251 time=102.4 ms As you could see ttl it's different for the same pix release... I HATE PIX, I HATE CISCO ;>
I've made a quick test with other PIX protected servers and it seems that when the packet passes the PIX it somehow resets the ttl for the original one. If I'm correct with these assumptions we have another method of fingerprinting PIX. Am I making any sense?? Fernando PS: Nice article about firewall fingerprinting: http://www.kmu-security.ch/identifyingfirewalls.htm
Fabio Pietrosanti ( naif ) E-mail: naif () sikurezza org PGP Key (DSS) http://naif.itapac.net/naif.asc -- Free advertising: www.openbsd.org Multiplatform Ultra-secure OS
Current thread:
- PIX and ttl Fernando Cardoso (May 24)
- RE: PIX and ttl Jason Lewis (May 25)
- RE: PIX and ttl Fernando Cardoso (May 25)
- Re: PIX and ttl Konstantin Rozinov (May 27)
- RE: PIX and ttl Jacek Lipkowski (May 25)
- RE: PIX and ttl Jason Lewis (May 26)
- RE: PIX and ttl Fernando Cardoso (May 25)
- <Possible follow-ups>
- Re: PIX and ttl Fabio Pietrosanti (naif) (May 25)
- RE: PIX and ttl Fernando Cardoso (May 25)
- Re: PIX and ttl Nelson Brito (May 26)
- RE: PIX and ttl Fernando Cardoso (May 25)
- Re: RE: PIX and ttl Fernando Cardoso (May 28)
- RE: RE: PIX and ttl Filipe Almeida (May 28)
- RE: RE: PIX and ttl Dario Ciccarone (May 28)
- RE: RE: PIX and ttl Filipe Almeida (May 28)
- Re: RE: RE: PIX and ttl Fernando Cardoso (May 28)
- Re: RE: RE: PIX and ttl Eugene Tsyrklevich (May 29)
- Re: RE: RE: PIX and ttl Fernando Cardoso (May 28)
- RE: PIX and ttl Jason Lewis (May 25)