DisablingProcesses

graememeyer edited this page Mar 16, 2017 · 11 revisions
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Disabling a process

If you've already run Setup and want to disable a certain sensor service, you can simply stop the running service and then change the corresponding config value from yes to no to prevent it from restarting the next time the NSM scripts are run.

For example, suppose you access Bro's HTTP logs via ELSA, so you want to disable http_agent to prevent those HTTP logs from being duplicated into the Sguil database. You would first stop the running http_agent service:

sudo nsm_sensor_ps-stop --only-http-agent

You would then edit /etc/nsm/$HOSTNAME-$INTERFACE/sensor.conf and change:

HTTP_AGENT_ENABLED="yes"

to:

HTTP_AGENT_ENABLED="no"

to prevent http_agent from restarting the next time the NSM scripts are run. A quick way to do this for all /etc/nsm/*/sensor.conf files on one box is to use the sed command as follows:

sudo sed -i 's|HTTP_AGENT_ENABLED="yes"|HTTP_AGENT_ENABLED="no"|g' /etc/nsm/*/sensor.conf

Sguil Agent

If you use the Sguil client and want to remove the disabled agent from Sguil's Agent Status tab, then stop sguild, set the sensor's active field to N in the database, and then restart sguild:

# Stop sguild
sudo nsm_server_ps-stop

# Set active="N", replacing HOSTNAME-INTERFACE-INSTANCE with your actual HOSTNAME, INTERFACE, and INSTANCE
sudo mysql --defaults-file=/etc/mysql/debian.cnf -Dsecurityonion_db -e 'update sensor set active="N" where hostname="HOSTNAME-INTERFACE-INSTANCE";'

# Restart sguild
sudo nsm_server_ps-start

Disabling Xplico

Disable Xplico in /etc/nsm/securityonion.conf:

sudo sed -i 's|XPLICO_ENABLED=yes|XPLICO_ENABLED=no|g' /etc/nsm/securityonion.conf

(Optional) Remove Xplico:

sudo apt-get purge xplico

Disabling Snorby

  1. Disable Snorby in the Apache configuration:

    sudo a2dissite snorby
    
  2. Reload Apache configuration:

    sudo service apache2 reload
    
  3. Prevent Snorby worker from starting on boot by setting SNORBY_ENABLED=no in /etc/nsm/securityonion.conf.

  4. Comment out the output database line in all barnyard2.conf files on ALL sensors:

    sudo sed -i 's|output database: alert, mysql, user=root dbname=snorby host=127.0.0.1|#output database: alert, mysql, user=root dbname=snorby host=127.0.0.1|g' /etc/nsm/*/barnyard2*.conf
    
  5. Restart barnyard2 on all sensors:

    sudo nsm_sensor_ps-restart --only-barnyard2
    

Disabling OSSEC

You can disable OSSEC as follows:

# Stop the running OSSEC processes 
sudo service ossec-hids-server stop

sudo update-rc.d -f ossec-hids-server disable

However, keep in mind that in addition to providing endpoint visibility from OSSEC agents, the OSSEC server also monitors and protects the Security Onion box itself. For example, suppose that you have an active adversary who is trying to compromise your Security Onion box. OSSEC may see those attempts and engage Active Response to block the attacker's IP address in the host-based firewall.