On Fri, Dec 20, 2019 at 12:15 PM Bruce Westbrook <bwestbr...@gmail.com> wrote:
>
> I'm having an issue getting a composite rule to trigger. What's really
> throwing me is that it works just fine when testing with ossec-logtest, but
> it doesn't work live.
>
> Here are the two rules in question:
>
> <rule id="100554" level="6">
> <if_sid>18101</if_sid>
> <id>^131$</id>
> <description>Server accepted initial RDP session request</description>
> <group>sysadmin,</group>
> </rule>
>
> <rule id="100560" level="15" frequency="3" timeframe="180">
> <if_matched_sid>100554</if_matched_sid>
> <description>ALERT: Potential RDP brute force attack</description>
> <group>sysadmin,recon,attacks,</group>
> </rule>
>
This seems like a silly idea, but it's the only one I have at the moment:
<rule id="100554" level="6">
<if_sid>18101</if_sid>
<id>^131$</id>
<description>Server accepted initial RDP session request</description>
<group>sysadmin,</group>
</rule>
<rule id="100560" level="15" frequency="3" timeframe="180">
<if_matched_sid>18101</if_matched_sid>
<id>^131$</id>
<description>ALERT: Potential RDP brute force attack</description>
<group>sysadmin,recon,attacks,</group>
</rule>
I'll try to look into it more when I find some time.
>
> ...and here is a sample log entry:
>
> 2019 Dec 20 11:28:59 WinEvtLog:
> Microsoft-Windows-RemoteDesktopServices-RdpCoreTS/Operational:
> INFORMATION(131): Microsoft-Windows-RemoteDesktopServices-RdpCoreTS: NETWORK
> SERVICE: NT AUTHORITY: server.domain: The server accepted a new TCP
> connection from client 10.104.248.199:57714.
>
>
> Using ossec-logtest I can enter this log entry and on the fifth time it fires
> off rule #100560 just as expected. But when I make those same five logon
> attempts to a live server, it only ever fires rule #100554. I've tried this
> up to 20 times in under 2 minutes, well within the rule timeframe, and it
> still never fires the composite rule alert, only 100554.
>
> I have quite a few other composite rules that I've written over the past few
> years and don't have this issue. I just don't see what the problem is with
> this one or why ossec-logtest shows it working but it never actually works in
> a live situation.
>
> I'm running OSSEC HIDS v2.9.3 on Linux, with the agents on Windows 2012+
> servers.
>
> Any thoughts?
>
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