Sorry Martin, got to go out now, but one last suggestion
Are you running the web-gui? If so, can you see the level 5 alerts as they arise? And again can you determine if those alerts are logging the IP? Andy From: ossec-list@googlegroups.com [mailto:ossec-list@googlegroups.com] On Behalf Of Martin Gottlieb Sent: Thursday, 28 April 2011 8:13 a.m. To: ossec-list@googlegroups.com Subject: Re: [ossec-list] Re: Active Response on Windows events Thanks, that does work. The problem is that when a real intruder is triggering my level 5 rule (100245), it is not recording the source IP, so it has no way of ever triggering the level 10 rule. That is what I am trying to figure out, why the decoder is not working properly "live" when it works fine using ossec-logtest. On 4/27/2011 4:01 PM, Andy Cockroft (andic) wrote: Hi You should be able to run ossec-logtest repeatedly (ie 6 times at least) with the same data, and you should see what it does in triggering the level 10 rule Andy From: ossec-list@googlegroups.com [mailto:ossec-list@googlegroups.com] On Behalf Of Martin Gottlieb Sent: Thursday, 28 April 2011 7:36 a.m. To: ossec-list@googlegroups.com Subject: Re: [ossec-list] Re: Active Response on Windows events good point, I should not be expecting email alerts on the level 5 rule. But since it's not recording the SrcIP value, it never triggers the level 10 rule, which I did also create: <rule id="100245" level="5"> <match>Logon Failure</match> <group>authentication_failed,</group> <description>User authentication failure.</description> </rule> <rule id="100246" level="10" frequency="5" timeframe="120" ignore="60"> <if_matched_sid>100245</if_matched_sid> <description>Windows brute force trying to get access to </description> <description>the system.</description> <same_source_ip /> <group>authentication_failures,</group> </rule> So my original question remains, why is it not able to extract the SrcIP address using the decoder that I created and verified using ossec-logtest? Thanks. Martin On 4/27/2011 3:27 PM, Andy Cockroft (andic) wrote: Hi This is triggering a level 5 alert - will that actually do anything on your system? Or do you have another rule for multiple occurrences? Certainly for mine, I have a level 10 alert for multiple occurrences (more than 3) which then activates the response on the windows agent Just a random thought Andy From: ossec-list@googlegroups.com [mailto:ossec-list@googlegroups.com] On Behalf Of Martin Gottlieb Sent: Thursday, 28 April 2011 1:23 a.m. To: ossec-list@googlegroups.com Subject: Re: [ossec-list] Re: Active Response on Windows events Well, I thought I was making progress, but now I'm not so sure. My MSSQL decoder has triggered a couple of active responses, so I believe it is working properly. But, I am not getting any alerts on windows logon failures (I did previously), much less an active response. I found the following event in my ossec alert log (identifying info modified): ** Alert 1303837130.3865847: - syslog,false_positivesauthentication_failed, 2011 Apr 26 12:58:50 (win3) 2.1.1.2->WinEvtLog Rule: 100245 (level 5) -> 'User authentication failure.' Src IP: (none) User: (none) WinEvtLog: Security: AUDIT_FAILURE(529): Security: SYSTEM: NT AUTHORITY: WINSERVER: Logon Failure: Reason: Unknown user name or bad password User Name: ryan Domain: WINSERVER Logon Type: 10 Logon Process: User32 Authentication Package: Negotiate Workstation Name: WINSERVER Caller User Name: WINSERVER$ Caller Domain: WINDOMAIN Caller Logon ID: (0x0,0x3E7) Caller Process ID: 5716 Transited Services: - Source Network Address: 7.7.7.226 Source Port: 51287 What's strange is that it does not match the SrcIP or User fields. When I run this log entry through ossec-logtest, I get the following results: **Phase 2: Completed decoding. decoder: 'winevt' dstuser: 'ryan' srcip: '7.7.7.226' **Phase 3: Completed filtering (rules). Rule id: '100245' Level: '5' Description: 'User authentication failure.' **Alert to be generated. So clearly the winevt decoder is working correctly. Any ideas as to why it works in test mode, but not "live"? Here's the winevt decoder: <decoder name="winevt"> <prematch>^WinEvtLog:\s*Security:\s*AUDIT_FAILURE\(\d+\):\s*Security\.* Logon Failure: </prematch> <regex offset="after_prematch">User Name:\s+(\w+) \.* Source Network Address:\s+(\d+.\d+.\d+.\d+)</regex> <order>user,srcip</order> </decoder> I did make a few minor changes since my previous posts, mainly replacing spaces with "\s*" to allow for multiple white-space characters. Thanks. Martin On 4/25/2011 11:43 AM, Martin Gottlieb wrote: Thanks, my ossec server is a router/firewall, my apologies for omitting this detail. I was really just trying to figure out how to get the server to trigger the script(s) in the first place on the windows events, since it was clearly getting notified about the events. With help from Andy, I believe I have found that the issue boils down to the decoders. I think I have a fix i place now and will be posting a "RESOLVED" message once I have verified this (just waiting for someone to attack the server). Thanks again to everyone who offered help on this. Martin On 4/25/2011 11:23 AM, Scott VR wrote: It is important to undertstand that firewall-drop.sh script executes unix/linux commands and the only way that invoking it on the server will serve any function to protect your windows hosts is if your ossec server is *also* running as a router/firewall in front of your windows boxes. If this is the case, it's a pretty major piece of the design that you left off of your description. If it's not the case, you are going to need something similar (which I think you alluded to in your inital email) to the null-route.cmd setup outlined in http://www.ossec.net/main/manual/manual-active-response-on-windows. In summary, if your ossec server is also a router for your network, then running the ipfilters/ipchains/ipsec commands in the firewall-drop.sh script will work, with the proper regex to obtain srcip. If it is not, the running this command on the ossec server will have no effect and you need to run the command on the windows box through its agent. Cheers, On Sat, Apr 23, 2011 at 10:27 PM, Martin Gottlieb <mar...@axion-it.net> wrote: Hi Andy, Thanks again for another great piece of advice. ossec-logtest seems to confirm that the regexes are good. The SQL Server decoder triggers rule 2501, level 5. I had to add the following to my local rules to get the winevt decoder to also trigger 2501: <rule id="100245" level="5"> <match>Logon Failure</match> <group>authentication_failed,</group> <description>User authentication failure.</description> </rule> I think this should to the trick. Thanks again for your help. Martin On 4/23/2011 5:26 PM, Andy Cockroft (andic) wrote: Hi I didn't have that much success with a Regex similar to the one you wrote, I ended up having to specify everything in a very long-handed way - as I said perhaps someone could write the decoder far more eloquently than I - especially constructs such as \.* in the middle of the Regex However, what I did do, is make my changes to the decoder and run ossec-logtest - this makes checking the decoder and rules so much easier without actually affecting production operation Best I can do for now - hope you have your Rules sorted as well - ossec-logtest will check these at the same time Andy From: ossec-list@googlegroups.com [mailto:ossec-list@googlegroups.com] On Behalf Of Martin Gottlieb Sent: Sunday, 24 April 2011 3:16 a.m. To: ossec-list@googlegroups.com Subject: Re: [ossec-list] Re: Active Response on Windows events Awesome, thanks! The events I'm seeing generally take 2 forms: SQL Server Events: WinEvtLog: Application: AUDIT_FAILURE(18456): MSSQLSERVER: (no user): no domain: WINSERVER: Login failed for user 'admin'. [CLIENT: 203.81.30.248] And general Windows Events: WinEvtLog: Security: AUDIT_FAILURE(529): Security: SYSTEM: NT AUTHORITY: WINSERVER: Logon Failure: Reason: Unknown user name or bad password User Name: admin Domain: WINSERVER Logon Type: 10 Logon Process: User32 Authentication Package: Negotiate Workstation Name: WINSERVER Caller User Name: WINSERVER$ Caller Domain: WINDOMAIN Caller Logon ID: (0x0,0x3E7) Caller Process ID: 532 &am p;nb sp; Transi ted Services: - Source Network Address: 7.7.7.109 Source Port: 3041 Would these work as the corresponding decoders: <decoder name="mssql"> <prematch>^WinEvtLog: Application: AUDIT_FAILURE\(\d+\): MSSQLSERVER: \.* Login failed for user</prematch> <regex offset="after_prematch">'(\w+)'. [CLIENT: (\d+.\d+.\d+.\d+)]</regex> <order>user,srcip</order> </decoder> <decoder name="winevt"> <prematch>^WinEvtLog: Security: AUDIT_FAILURE\(\d+\): Security\.* Logon Failure: </prematch> <regex offset="after_prematch">User Name: (\w+) \.* Source Network Address: (\d+.\d+.\d+.\d+)</regex> <order>user,srcip</order> </decoder> Thanks. Martin On 4/22/2011 7:28 PM, AndiC wrote: The problem I found was that the Windows decoder in the server /dev/ ossec/etc/decoder.xml does not extract the "srcip", so you have nothing to work with to block Now this is what I replaced mine with: <decoder name="windows"> <type>windows</type> <prematch>^WinEvtLog: </prematch> <regex offset="after_prematch">^\.+: (\w+)\((\d+)\): (\.+): </regex> <regex>(\.+): \.+: (\S+):</regex> <regex> \.+: \.+: \.+: \.+: \.+: \.+: </regex> <regex>\.+: \.+: \.+: \.+: \.+: \.+: \.+: \.+:</regex> <regex>\.(\S+)</regex> <order>status, id, extra_data, user, system_name, srcip</order> <fts>name, location, user, system_name</fts> </decoder> Then, in /dev/ossec/rules/msauth.xml, I replaced rule 18152 with: <rule id="181521" level="10" frequency="$MS_FREQ" timeframe="240"> <if_matched_group>win_authentication_failed</if_matched_group> <same_source_ip /> <description>Multiple Windows Logon Failures Same IP.</ description> <group>authentication_failures,</group> </rule> <rule id="181522" level="10" frequency="$MS_FREQ" timeframe="240"> <if_matched_group>win_authentication_failed</if_matched_group> <description>Multiple Windows Logon Failures.</description> <group>authentication_failures,</group> </rule> I also dropped $MS_FREQ (start of msauth.xml) to 3 This works for me, and my Windows clients are well protected. I am sure someone could write a far more eloquent decode Regex - sorry I'm just coming to grips with that. I'm also uncertain if this will work against anything other than Server 2003 for which it is written But this is only the decoder that needs some tuning, the rest seems fine Regards Andy On Apr 23, 9:08 am, Martin Gottlieb <mar...@axion-it.net> <mailto:mar...@axion-it.net> wrote: Shouldn't this block from the config on the OSSEC server: <active-response> <!-- Firewall Drop response. Block the IP for - 600 seconds on the firewall (iptables, - ipfilter, etc). --> <command>firewall-drop</command> <location>as</location> <level>6</level> <timeout>3600</timeout> </active-response> cause the firewall drop script to be run on the server for any event that is level 6 or higher, regardless of which agent it came from? That's all I'm trying to accomplish, I don't need anything to run on the Windows agent if I can get the firewall drop script to run on the server. Thanks. Martin On 4/22/2011 4:58 PM, dan (ddp) wrote: Hi Martin, On Fri, Apr 22, 2011 at 4:37 PM, Martin Gottlieb<mar...@axion-it.net> <mailto:mar...@axion-it.net> wrote: I guess what I'm trying to understand is this: When an event is triggered from a Linux agent, the firewall drop script is run on the OSSEC server (in addition to the hosts deny script being called on the agent). I don't recall doing anything special to make this happen when I installed OSSEC, I assume it is part of the default behavior. The default actions (if I'm reading https://bitbucket.org/dcid/ossec-hids/src/4908b28513b0/etc/ossec-serv... correctly) is that the script is run on the system where the log message originated. Unless you changed the configurations the scripts shouldn't be running on both the server and the agents. When an event is triggered on a Windows agent, the firewall drop script is NOT called on the server, but I would like it to be. I would like the default behavior on Windows agents to be the same as Linux agents, at least as far as what happens on the OSSEC server. The Windows agent is obviously reporting the event to the server as it logs it and reports it to me. Am I understanding the responses so far to mean that I have to write a script to make this happen, and that the script needs to reside on the Windows agent? Thanks again. Martin The script would have to reside on all of the systems you want it to run on. Having it run on both Windows and Linux systems may be difficult.- Hide quoted text - - Show quoted text -
