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: [email protected] [mailto:[email protected]] On Behalf Of Martin Gottlieb Sent: Sunday, 24 April 2011 3:16 a.m. To: [email protected] 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 Transited Services: - Source Network Address: 118.126.5.109 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 <[email protected]> <mailto:[email protected]> 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<[email protected]> <mailto:[email protected]> 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 -
