-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Greetings! A quite known proxy vulnerability was found for FW1 V4.1 SP5 (plus hotfixes) - thanks to Ryan Snyder for announcing the first bits on Firewall-1 mailing list. If you connect to a server you are allowed to connect to via HTTP proxy (e.g. a common rule is "Any / WebServer / http->ressource"). Then use the CONNECT method to connect to a different server, e.g. an internal mailserver. Example: you = 6.6.6.666 Webserver = 1.1.1.1 Internal Mailserver = 2.2.2.2 Rule allows: Any Webserver http->ressource connect with "telnet 1.1.1.1 80" to the webserver and enter CONNECT 2.2.2.2:25 / HTTP/1.0 response: mail server banner - and running SMTP session e.g. to send SPAM from. You can connect to any TCP port on any machine the firewall can connect to. Telnet, SMTP, POP, etc. Restrictions found: - connects are only possible if the firewall module is allowed access (i.e. via policy/properties, specific rules or "Any (dst) (svc)..." rules - you have to allow "CONNECT" - is enabled if you allowed "Tunneling" (General tab) connection method or did not delete the "*" in "Other" Methods (Match tab) Fast workarounds: - Change your ressource settings to filter out CONNECT commands, i.e. * disable HTTP tunneling * check that "Other" method is specified NOT to match CONNECT (i.e. remove the default wildcard) - disallow access from the firewall module (->Properties) - replace in all your rules containing the service HTTP+Resource this part with plain HTTP. Yes, you loose some content security but at least you don't compromise your other servers The thing that really concerns me is, that this general problem has been known to be an issue with plain HTTP proxies like the Squid since ages (see e.g. http://www.squid-cache.org/Doc/FAQ/FAQ-10.html#ss10.14). And why didn't Checkpoint prevent or at least document this? Puzzled Volker - -- - ------------------------------------------------------------------- volker.tanger@discon.de discon GmbH IT-Security Consulting Wrangelstrasse 100 http://www.discon.de/ 10997 Berlin, Germany - ------------------------------------------------------------------- PGP-Fingerprint: 5323 a4f7 a7c2 b8ef 4653 05ce d2ea 2b74 b94c c68e -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (MingW32) - WinPT v0.0.3 (WINNT) Comment: This is the WinPT config test iEYEARECAAYFAjxyaZgACgkQ0uordLlMxo6yhQCeIzM/tWK3HCEVM/V816WSFpgh YhMAoJX/uDKzPE1NKO9XKzizs3sxZWiW =XumZ -----END PGP SIGNATURE-----
