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>
[mailto:ossec-list@googlegroups.com] *On Behalf Of *Martin Gottlieb
*Sent:* Sunday, 24 April 2011 3:16 a.m.
*To:* ossec-list@googlegroups.com
<mailto: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 <tel: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 Transi
ted 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<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 -
