To start, you need to enable active response on Windows (disabled by default). To do that, just add the following to the agent’s ossec.conf:
<active-response> <disabled>no</disabled> </active-response>
After that, you need to go to the manager and specify when to run the response. Adding the following to ossec.conf will enable the responses for alerts above level 6:
<command> <name>win_nullroute</name> <executable>route-null.cmd</executable> <expect>srcip</expect> <timeout_allowed>yes</timeout_allowed> </command> <active-response> <command>win_nullroute</command> <location>local</location> <level>6</level> <timeout>600</timeout> </active-response>
With the configuration completed (and the manager restarted), you can test the active response by running the agent-control script (in this case, I am running it on agent id 185 to block ip 126.96.36.199):
# /var/ossec/bin/agent_control -L OSSEC HIDS agent_control. Available active responses: Response name: host-deny600, command: host-deny.sh Response name: firewall-drop600, command: firewall-drop.sh Response name: win_nullroute600, command: route-null.cmd # /var/ossec/bin/agent_control -b 188.8.131.52 -f win_nullroute600 -u 185 OSSEC HIDS agent_control: Running active response "win_nullroute600′ "n: 185
And looking at the agent you should see the new entry in the route table:
C:\>route print .. Active Routes: Network Destination Netmask Gateway Interface Metric 184.108.40.206 255.255.255.255 x.y.z x.y.z 1 ..
If you run into any issues, look at the ossec.log file (on the agent) for any entry for ossec-execd. If you enabled it correctly, you will see:
2008/08/20 11:53:49 ossec-execd: INFO: Started (pid: 3896).