Snort mailing list archives
tcp port 0 rule
From: Bob Van Cleef <vancleef () microunity com>
Date: Fri, 11 Oct 2002 09:51:37 -0700 (PDT)
Saw the following scan entry in my alert log: [**] [1:524:3] BAD TRAFFIC tcp port 0 traffic [**] [Classification: Misc activity] [Priority: 3] 10/09-02:34:18.941743 80.131.131.116:0 -> 192.86.6.8:0 TCP TTL:242 TOS:0x0 ID:65259 IpLen:20 DgmLen:40 *****R** Seq: 0xE59FF019 Ack: 0xE5B5A1E5 Win: 0xF018 TcpLen: 20 However, when I looked into the rules I noted the following: bad-traffic.rules:alert tcp $EXTERNAL_NET any <> $HOME_NET 0 (msg:"BAD TRAFFIC tcp port 0 traffic"; reference:cve,CVE-1999-0675; reference:nessus,10074; classtype:misc-activity; sid:524; rev:4;) The test is for TCP port 0, however the CVE-1999-0675 reference states: http://icat.nist.gov/icat.cfm?cvename=CVE-1999-0675 "Firewall-1 can be subjected to a denial of service via UDP packets that are sent through VPN-1 to port 0 of a host." So, two questions: 1 - if the attack is UDP based, why is the rule looking at TCP? 2 - is there anything wrong with TCP port 0 connection attempts? http://mini.net/tcl/2230 The process can let the system automatically assign a port. For both the Internet domain and the XNS domain, specifying a port number of 0 before calling bind() requests the system to do this. Bob ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://www.geocrawler.com/redir-sf.php3?list=snort-users
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- tcp port 0 rule Bob Van Cleef (Oct 11)