Snort mailing list archives
Re: why UDP disc acquire?
From: "Al Lewis (allewi)" <allewi () cisco com>
Date: Sat, 25 Jun 2016 13:36:54 +0000
See below.. This is with the conf and pcap attached. It alerts as expected and UDP traffic isn’t discarded. cliffjumper$ ./bin/snort -c etc/ISAKMP-ISSUE.conf -r etc/ISAKMP-ISSUE-2.pcap -Acmg -H -U -k none -q 06/21-12:36:53.127741 [**] [1:1000001:1] DOS Nbisakmp [**] [Priority: 0] {UDP} 10.0.0.1:500 -> 10.0.0.2:500 06/21-12:36:53.127741 C2:00:57:75:00:00 -> C2:01:57:75:00:00 type:0x800 len:0xBE 10.0.0.1:500 -> 10.0.0.2:500 UDP TTL:255 TOS:0xC0 ID:101 IpLen:20 DgmLen:176 Len: 148 CF 02 32 6F 14 A9 5B 93 00 00 00 00 00 00 00 00 ..2o..[......... 01 10 02 00 00 00 00 00 00 00 00 94 0D 00 00 3C ...............< 00 00 00 01 00 00 00 01 00 00 00 30 01 01 00 01 ...........0.... 00 00 00 28 01 01 00 00 80 01 00 07 80 0E 00 80 ...(............ 80 02 00 02 80 04 00 01 80 03 00 01 80 0B 00 01 ................ 00 0C 00 04 00 01 51 80 0D 00 00 14 43 9B 59 F8 ......Q.....C.Y. BA 67 6C 4C 77 37 AE 22 EA B8 F5 82 0D 00 00 14 .glLw7."........ 7D 94 19 A6 53 10 CA 6F 2C 17 9D 92 15 52 9D 56 }...S..o,....R.V 00 00 00 14 90 CB 80 91 3E BB 69 6E 08 63 81 B5 ........>.in.c.. EC 42 7B 1F .B{. =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ cliffjumper$ cat etc/ISAKMP-ISSUE.conf | grep sid:1 alert udp any 500 -> any 500 (msg:"DOS Nbisakmp"; sid:1000001; rev:1;) cliffjumper$ ./bin/snort -V ,,_ -*> Snort! <*- o" )~ Version 2.9.8.2 GRE (Build 335) '''' By Martin Roesch & The Snort Team: http://www.snort.org/contact#team Copyright (C) 2014-2015 Cisco and/or its affiliates. All rights reserved. Copyright (C) 1998-2013 Sourcefire, Inc., et al. Using libpcap version 1.5.3 - Apple version 54 Using PCRE version: 8.38 2015-11-23 Using ZLIB version: 1.2.5 Albert Lewis QA SNORT/Sourcefire SOURCEfire, Inc. now part of Cisco 9780 Patuxent Woods Drive Columbia, MD 21046 Phone: (office) 443.430.7112 Email: allewi () cisco com<mailto:allewi () cisco com> From: allewi <allewi () cisco com<mailto:allewi () cisco com>> Date: Saturday, June 25, 2016 at 9:22 AM To: Andrei_1980 <andrei_1980 () mail ru<mailto:andrei_1980 () mail ru>>, 'snort-users' <snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>> Subject: Re: [Snort-users] why UDP disc acquire? You may need to adjust your wireshark settings. Wireshark lists them as “malformed ISAKMP” packets. Albert Lewis QA SNORT/Sourcefire SOURCEfire, Inc. now part of Cisco 9780 Patuxent Woods Drive Columbia, MD 21046 Phone: (office) 443.430.7112 Email: allewi () cisco com<mailto:allewi () cisco com> From: Andrei_1980 <andrei_1980 () mail ru<mailto:andrei_1980 () mail ru>> Date: Saturday, June 25, 2016 at 5:01 AM To: allewi <allewi () cisco com<mailto:allewi () cisco com>>, 'snort-users' <snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>> Subject: Re: [Snort-users] why UDP disc acquire? Why you think that udp packet malformed? Tools like wireshark, tcpdump and tcpreplay handle it correctly. This packets have only wrong checksum, but i disable checksum control in Snort by using option "-k none". 24.06.2016 19:05, Al Lewis (allewi) пишет: It looks like snort is discarding them because they are all malformed. Albert Lewis QA SNORT/Sourcefire SOURCEfire, Inc. now part of Cisco 9780 Patuxent Woods Drive Columbia, MD 21046 Phone: (office) 443.430.7112 Email: <mailto:allewi () cisco com> allewi () cisco com<mailto:allewi () cisco com> From: Andrei_1980 <<mailto:andrei_1980 () mail ru>andrei_1980 () mail ru<mailto:andrei_1980 () mail ru>> Date: Friday, June 24, 2016 at 11:28 AM To: allewi <<mailto:allewi () cisco com>allewi () cisco com<mailto:allewi () cisco com>>, 'snort-users' <snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>> Subject: Re: [Snort-users] why UDP disc acquire? hmm, strange. I,m attach pcap to first message. Ok reatach to this message. On 24.06.2016 18:22, Al Lewis (allewi) wrote: Hello, Can you provide us with the pcap or a sample of it? Albert Lewis QA SNORT/Sourcefire SOURCEfire, Inc. now part of Cisco 9780 Patuxent Woods Drive Columbia, MD 21046 Phone: (office) 443.430.7112 Email: <mailto:allewi () cisco com> allewi () cisco com<mailto:allewi () cisco com> From: Andrei_1980 <andrei_1980 () mail ru<mailto:andrei_1980 () mail ru>> Date: Friday, June 24, 2016 at 11:06 AM To: 'snort-users' <snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>> Subject: [Snort-users] why UDP disc acquire? Hi all. I use snort 2.9.8.2 A have some pcap file for old attack (see attach) . It contain only udp packets. I wrote test rule: alert udp any 500 -> any 500 (msg:"DOS Nbisakmp"; classtype: attempted-dos; sid:1000001; rev:1;) and run snort: snort -c ./etc/snort.conf -A console -K none -k none -r ./pcaps/DOS_Nbisakmp.pcap and get no alerts. In output stats i have: ........... Packet I/O Totals: Received: 100 Analyzed: 100 (100.000%) Dropped: 0 ( 0.000%) Filtered: 0 ( 0.000%) Outstanding: 0 ( 0.000%) Injected: 0 ..................... Breakdown by protocol (includes rebuilt packets): Eth: 100 (100.000%) VLAN: 0 ( 0.000%) IP4: 100 (100.000%) Frag: 0 ( 0.000%) ICMP: 0 ( 0.000%) UDP: 100 (100.000%) ................... UDP Disc: 100 (100.000%) ICMP Disc: 0 ( 0.000%) All Discard: 100 (100.000%) (full output and snort.conf see in attach) If i change rule (udp to ip) : alert ip any 500 -> any 500 (msg:"DOS Nbisakmp"; classtype: attempted-dos; sid:1000001; rev:1;) all packets generate alerts. So, why UDP packets in sample pcap discarded if i use udp protocol in alert?
Attachment:
ISAKMP-ISSUE.conf
Description: ISAKMP-ISSUE.conf
Attachment:
ISAKMP-ISSUE-2.pcap
Description: ISAKMP-ISSUE-2.pcap
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Current thread:
- why UDP disc acquire? Andrey Kiryukhin (Jun 24)
- Re: why UDP disc acquire? Al Lewis (allewi) (Jun 24)
- Re: why UDP disc acquire? Andrey Kiryukhin (Jun 24)
- Re: why UDP disc acquire? Al Lewis (allewi) (Jun 24)
- Re: why UDP disc acquire? Andrey Kiryukhin (Jun 25)
- Re: why UDP disc acquire? wkitty42 (Jun 25)
- Re: why UDP disc acquire? Andrey Kiryukhin (Jun 25)
- Re: why UDP disc acquire? Al Lewis (allewi) (Jun 25)
- Re: why UDP disc acquire? Al Lewis (allewi) (Jun 25)
- Re: why UDP disc acquire? Andrey Kiryukhin (Jun 24)
- Re: why UDP disc acquire? Al Lewis (allewi) (Jun 24)