I don't at this time. Since the firewall is stopping the packets, they're not getting through to my IDS. I'm setting up a sniffer outside the firewall to capture traffic so I can get full packet dumps. My PIX is running the latest software in the 5.3 line. I suppose it's possible that it's misreporting, but the odd thing is that I've been reading the PIX logs for 5 months now, and I just started seeing large numbers of these packets within the past two days. We've had gnutella users for ages, but it's never caused issues like this before. The other really odd thing is that all of these packets are different. It's not like there's a standard signature... ACK FIN URG set or something. Some have two flags, some have three, some have all six, some have none. It really seems like someone is manipulating these packets. I'll send some packet dumps along when I get them. |---------+----------------------------> | | Robert Buckley | | | <rbuckley@synapse| | | mail.com> | | | | | | 05/10/2002 11:00 | | | AM | | | | |---------+----------------------------> >--------------------------------------------------------------------------------------------------------------------| | | | To: "'pbsarnacat_private'" <pbsarnacat_private>, incidentsat_private | | cc: | | Subject: RE: Strange TCP headers | >--------------------------------------------------------------------------------------------------------------------| pb, That is strange. Do you have some raw data to back up what pix is saying. If you have an old IOS running there, it could very well be pix is not reporting correctly. We need to verify this by looking at the actual raw header, and see if it has options etc. I've caught a few people on my own network using gnutella, which is prohibited by policy, but I've never seen our pix's report bad header lengths on the traffic. -----Original Message----- From: pbsarnacat_private [mailto:pbsarnacat_private] Sent: Friday, May 10, 2002 11:40 AM To: incidentsat_private Subject: Strange TCP headers I just joined the list, and a quick search of the archives didn't turn this up, but forgive me if this has already been discussed. Starting on May 8 and continuing on through today, my firewall has been picking up malformed TCP packets. The PIX complains about bad header lengths, but the flag combinations that are showing up are extremely strange. The source IP addresses are varied, and the destination IPs are all NAT'd client workstations... not servers. The interesting thing is that a majority of the scans are originating from port 6346, which snort.org informs me is the gnutella server port. I've verified that at least two of the clients that these packets were directed to were running various file-sharing clients. Is this some sort of new scanning tool that runs over the Gnutella network? Anyone have any thoughts? (See attached file: 5-10-02-scans.txt) Thanks! Patrick Sarnacke ---------------------------------------------------------------------------- This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com
This archive was generated by hypermail 2b30 : Fri May 10 2002 - 10:28:59 PDT