Snort mailing list archives
Re: Snort3 IPS questions, issues, and requests
From: Noah Dietrich <noah_dietrich () 86penny org>
Date: Thu, 23 Nov 2017 07:12:46 +0200
Hi Russ, Regarding the segfault, after a little further testing the issue appears to occur whenever you don't use all lowercase for your rule options (msg, gid, sid, et cetera). for example, this rule works: alert icmp any any -> $HOME_NET any (msg:"ICMP test detected"; sid:10000001; rev:001; gid:1; classtype:icmp-event;) but any of the following throw a segfault: alert icmp any any -> $HOME_NET any (msg:"ICMP test detected"; sid:10000001; rev:001; GID:1; classtype:icmp-event;) alert icmp any any -> $HOME_NET any (msg:"ICMP test detected"; Sid:10000001; rev:001; gid:1; classtype:icmp-event;) alert icmp any any -> $HOME_NET any (Msg:"ICMP test detected"; sid:10000001; rev:001; gid:1; classtype:icmp-event;) let me know if you need more information. my configuration and output is below. Thanks, noah Details of my configuration: snort3 build 240 on Ubuntu 16 x64 with all the additional software installed (let me know if I've missed any optional software packages): noah@snort3:/etc/snort$ /bin/snort -V ,,_ -*> Snort++ <*- o" )~ Version 3.0.0 (Build 240) from 2.9.8-383 '''' By Martin Roesch & The Snort Team http://snort.org/contact#team Copyright (C) 2014-2017 Cisco and/or its affiliates. All rights reserved. Copyright (C) 1998-2013 Sourcefire, Inc., et al. Using DAQ version 2.2.2 Using LuaJIT version 2.0.4 Using OpenSSL 1.0.2g 1 Mar 2016 Using libpcap version 1.7.4 Using PCRE version 8.38 2015-11-23 Using ZLIB version 1.2.8 Using FlatBuffers 1.7.0 Using Hyperscan version 4.6.0 2017-11-18 Using LZMA version 5.1.0alpha *Files used:* noah@snort3:/etc/snort$ tree . ├── builtin_rules ├── file_magic.lua ├── lists ├── rules │ ├── ips.include │ ├── local.rules │ ├── sid-msg.map │ └── snort3-community.rules ├── snort_defaults.lua ├── snort.lua └── so_rules *# snort_defaults.lua *(relevant sections): --------------------------------------------------------------------------- -- default paths --------------------------------------------------------------------------- -- Path to your rules files (this can be a relative path) RULE_PATH = '/etc/snort/rules' BUILTIN_RULE_PATH = '/etc/snort/builtin_rules' PLUGIN_RULE_PATH = '/etc/snort/so_rules' -- If you are using reputation preprocessor set these WHITE_LIST_PATH = '/etc/snort/lists' BLACK_LIST_PATH = '/etc/snort/lists' *# snort.lua *(relevant sections) --------------------------------------------------------------------------- -- 2. configure defaults --------------------------------------------------------------------------- -- HOME_NET and EXTERNAL_NET must be set now -- setup the network addresses you are protecting HOME_NET = '10.0.0.0/24' -- set up the external network addresses. -- (leave as "any" in most situations) EXTERNAL_NET = 'any' dofile(conf_dir .. '/snort_defaults.lua') dofile(conf_dir .. '/file_magic.lua') appid = { -- appid requires this to use appids in rules app_detector_dir = '/lib', log_stats = true, } ips = { -- use this to enable decoder and inspector alerts -- enable_builtin_rules = true, -- use include for rules files; be sure to set your path -- note that rules files can include other rules files --include = 'snort3_community.rules' include = RULE_PATH .. '/ips.include', } *# ips.include* #include rules/snort3-community.rules include rules/local.rules *# local.rules* alert icmp any any -> $HOME_NET any (msg:"ICMP test detected"; sid:10000001; rev:001; GID:1; classtype:icmp-event;) *# Running Snort (and getting segfault):* noah@snort3:/etc/snort$ sudo /bin/snort -c /etc/snort/snort.lua --warn-all -------------------------------------------------- o")~ Snort++ 3.0.0-240 -------------------------------------------------- Loading /etc/snort/snort.lua: ssh pop binder stream_tcp gtp_inspect dce_http_proxy stream_icmp normalizer ftp_server stream_udp modbus ips ssl latency wizard appid file_id ftp_data back_orifice smtp port_scan dce_http_server dce_tcp dce_smb telnet classifications sip rpc_decode http_inspect stream_ip stream_user dnp3 ftp_client stream references arp_spoof dns dce_udp imap stream_file Finished /etc/snort/snort.lua. Loading /etc/snort/rules/ips.include: Loading rules/local.rules: Segmentation fault (core dumped) noah@snort3:/etc/snort$ When i fix the rules to have all lowercase option names, i don't get a segfault: noah@snort3:/etc/snort$ sudo /bin/snort -c /etc/snort/snort.lua --warn-all -------------------------------------------------- o")~ Snort++ 3.0.0-240 -------------------------------------------------- Loading /etc/snort/snort.lua: ssh pop binder stream_tcp gtp_inspect dce_http_proxy stream_icmp normalizer ftp_server stream_udp modbus ips ssl latency wizard appid file_id ftp_data back_orifice smtp port_scan dce_http_server dce_tcp dce_smb telnet classifications sip rpc_decode http_inspect stream_ip stream_user dnp3 ftp_client stream references arp_spoof dns dce_udp imap stream_file Finished /etc/snort/snort.lua. Loading /etc/snort/rules/ips.include: Loading rules/local.rules: Finished rules/local.rules. Finished /etc/snort/rules/ips.include. -------------------------------------------------- rule counts total rules loaded: 1 text rules: 1 option chains: 1 chain headers: 1 -------------------------------------------------- port rule counts tcp udp icmp ip any 0 0 1 0 total 0 0 1 0 WARNING: port rule 1:10000001:1 has no fast pattern WARNING: legacy mode fast pattern searching enabled -------------------------------------------------- pcap DAQ configured to passive. -------------------------------------------------- memory (heap) main thread usage: 26400128 allocations: 138043 deallocations: 77420 thread cap: 0 preemptive threshold: 0 Snort successfully validated the configuration (with 2 warnings). o")~ Snort exiting On Mon, Nov 20, 2017 at 5:24 PM, Russ <rucombs () cisco com> wrote:
Hey Noah, responses inline. Thanks Russ On 11/19/17 3:36 AM, Noah Dietrich wrote: Hello, While working with Snort3 (build 240), I have found some issues, and have a few questions and requests. I am happy to submit these through Github if you'd like. This is fine. Whatever works for you. 1. What is the difference between *ips.include* and *ips.rules*? From the manual and examples, it looks like ips.include is for legacy rules (although snort3 community rules load fine), while ips.rules is for local rules in the same file. can you clarify? ips.include = filename of Snort 3.0 rules you want to load. Like Snort 2.X, you can put include statements in that file to include other files. Snort 3.0 will not load Snort 2.X rules (but you can use snort2lua to convert them). ips.rules = string variable containing rules directly in the Lua file. This is good for simple rules or test configurations or enabling specific builtins like this: local_rules = [[ block ( gid:119; sid:16; ) block ( gid:119; sid:32; ) ]] ips = { rules = local_rules } 2. For best practices, are you expecting people to set *$RULE_HOME* in *snort_defaults.lua*, or should this be overwritten in *snort.lua*? Should this be moved to snort.lua, since the word 'defaults' seems to indicate something the user shouldn't change. I am not familiar with RULE_HOME, but obviously those files are just starting points and should be modified to meet your needs. That said, my suggestion would be to just edit snort.lua and copy/paste/tweak stuff from snort_defaults.lua into snort.lua or elsewhere. That way you can more easily absorb any changes to snort_defaults.lua. 3. If $RULE_HOME is set, when referencing rule files, you are now required to have all rules under that folder (with no explicit paths to other locations). This seems like a bug. It would be nice if relative files would use the $RULES_HOME directory, while full paths to rule files would not use $RULE_HOME. Are you referring to RULE_PATH? Regardless, there is no restriction on where your rules are located or on including one file from another. Snort++ intentionally doesn't start guessing about the location of stuff so I wouldn't call that a bug. Sounds like adding a command line option that says look for all rules files starting with a given path will do what you want. 4. When using *ips.include* with a file that lists all rule files (example below), the file paths don't seem to be relative to $RULE_HOME, but are relative to the snort.lua file, which seems odd. By default, everything should be relative to your current working directory, which seems normal. :) How is this different from #3? 5. It would be nice to be able to specify multiple rule files in your snort.lua, rather than listing them all in ips.include (or whatever). The current method of lincluding a list of rule files in a text file referenced from *ips.include *seems like a kludge and adds an extra layer of work and increases the chance of an issue when configuring your rules. A comma-seperated list of files (relative to $RULE_HOME or full paths) would be helpful. Would this work for you (assuming the new command line option mentioned in #3)? local_rules = [[ include one.rules include two.rules # ... ]] ips = { rules = local_rules } 6. Not sure if this is an issue or not, but if you specify the GID keyword in a rule loaded with *ips.include*, snort3 will segfault. Oops. Any segfault is an issue but I'm unable to reproduce that. Can you isolate it and send the rule? Thank you, Noah Here is how my system is configured for the above questions (relevant sections only): */etc/snort/snort_defaults.lua:* RULE_PATH = '/etc/snort/rules' */etc/snort/**snort.lua* ips = { enable_builtin_rules = true, include = RULE_PATH .. '/ips.include', } */etc/snort/rules/ips.include* include rules/snort3-community.rules include rules/local.rules ls -l /etc/snort/rules -rw-r--r-- 1 root root 64 Nov 19 09:33 ips.include -rw-r--r-- 1 root root 1389 Nov 19 09:36 local.rules -rw-r--r-- 1 root root 376241 Nov 18 13:42 sid-msg.map -rw-r--r-- 1 root root 1504089 Nov 18 13:36 snort3-community.rules *noah@snort3:/etc/snort$ /bin/snort -V* ,,_ -*> Snort++ <*- o" )~ Version 3.0.0 (Build 240) from 2.9.8-383 '''' By Martin Roesch & The Snort Team http://snort.org/contact#team Copyright (C) 2014-2017 Cisco and/or its affiliates. All rights reserved. Copyright (C) 1998-2013 Sourcefire, Inc., et al. Using DAQ version 2.2.2 Using LuaJIT version 2.0.4 Using OpenSSL 1.0.2g 1 Mar 2016 Using libpcap version 1.7.4 Using PCRE version 8.38 2015-11-23 Using ZLIB version 1.2.8 Using FlatBuffers 1.7.0 Using Hyperscan version 4.6.0 2017-11-18 Using LZMA version 5.1.0alpha _______________________________________________ Snort-devel mailing listSnort-devel@lists.snort.orghttps://lists.snort.org/mailman/listinfo/snort-devel Please visit http://blog.snort.org for the latest news about Snort!
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Current thread:
- Snort3 IPS questions, issues, and requests Noah Dietrich (Nov 19)
- Re: Snort3 IPS questions, issues, and requests Russ via Snort-devel (Nov 20)
- Re: Snort3 IPS questions, issues, and requests Noah Dietrich (Nov 22)
- Re: Snort3 IPS questions, issues, and requests Russ via Snort-devel (Nov 24)
- Re: Snort3 IPS questions, issues, and requests Russ via Snort-devel (Nov 28)
- Re: Snort3 IPS questions, issues, and requests Noah Dietrich (Nov 22)
- Re: Snort3 IPS questions, issues, and requests Russ via Snort-devel (Nov 20)