Monitoring running processes

Create a batch script named tasklist.bat in the C:\ directory of the Windows endpoint and add the following content. The script adds a tasklist header to the output of the tasklist command:

@Echo Off
setlocal enableDelayedExpansion

for /f "delims=" %%a in ('powershell -command "& tasklist"') do (
    echo tasklist: %%a
)

exit /b

Append the following configuration to the Wazuh agent’s C:\Program Files (x86)\ossec-agent\ossec.conf file. The tasklist command lists running processes on Windows endpoints:

<ossec_config>
  <wodle name="command">
    <disabled>no</disabled>
    <tag>tasklist</tag>
    <command>PowerShell.exe C:\tasklist.bat</command>
    <interval>2m</interval>
    <run_on_start>yes</run_on_start>
    <timeout>10</timeout>
  </wodle>
</ossec_config>

Where:

• The PowerShell.exe C:\tasklist.bat value in the <command> tag is the command to be executed by the Command module. As seen, the PowerShell executable is used to execute the C:\tasklist.bat script.

• The value 2m in the <interval> tag indicates that the Command module runs the command every 2 minutes.

Restart the Wazuh agent to apply the changes, using PowerShell with administrator privileges:

> Restart-Service -Name wazuh

Add the following decoder to the /var/ossec/etc/decoders/local_decoder.xml file:

<decoder name="tasklist">
  <prematch>^tasklist: </prematch>
</decoder>

Add the rule below to the /var/ossec/etc/rules/local_rules.xml file to generate an alert when the notepad.exe process is running:

<group name="process_monitor,">
  <rule id="100010" level="6">
    <decoded_as>tasklist</decoded_as>
    <regex type="pcre2">(?i)notepad.exe</regex>
    <description>Notepad.exe is running.</description>
  </rule>
</group>

Restart the Wazuh manager to apply the changes:

$ sudo systemctl restart wazuh-manager

Append the Logcollector module configuration below to the Wazuh agent /var/ossec/etc/ossec.conf file:

<ossec_config>
  <localfile>
    <log_format>full_command</log_format>
    <command>ps -auxw</command>
    <frequency>120</frequency>
  </localfile>
</ossec_config>

Where:

• The full_command value in the <log_format> tag specifies the output of the command is read as a single event.

• The value ps -auxw in the <command> tag specifies the command the Logcollector module executes.

• The value 120 in the <frequency> tag specifies the command runs every 120 seconds (2 minutes).

Restart the Wazuh agent service to apply the changes:

$ sudo systemctl restart wazuh-agent

Add the rules below to the /var/ossec/etc/rules/local_rules.xml file. The rules generate an alert when the /usr/sbin/cron process is not running as expected:

<group name="process_monitor,">
  <rule id="100012" level="6">
    <if_sid>530</if_sid>
    <match>^ossec: output: 'ps -auxw'</match>
    <description>Cron process not running.</description>
  </rule>

  <rule id="100013" level="0">
    <if_sid>100012</if_sid>
    <match>/usr/sbin/cron</match>
    <description>Cron process is running as expected.</description>
  </rule>
</group>

The first rule with ID 100012 generates an alert ("Cron process not running.") unless it is overridden by its child rule with ID 100013 that matches /usr/sbin/cron in the command output. You can add as many child rules as needed to enumerate all of the important processes you want to monitor.

Restart the Wazuh manager to apply the changes:

$ sudo systemctl restart wazuh-manager

Append the following configuration to the Wazuh agent /Library/Ossec/etc/ossec.conf file:

<ossec_config>
  <localfile>
    <log_format>full_command</log_format>
    <command>ps auxw | grep -i [C]alendar.app</command>
    <alias>check_calendar_status</alias>
    <frequency>120</frequency>
  </localfile>
</ossec_config>

Where:

• The full_command value in the <log_format> tag specifies the output of the command is read as a single event.

• The value ps auxw | grep -i [C]alendar.app in the <command> tag is the command the Logcollector module executes to check the state of the Calendar application.

• The value check_calendar_status in the <alias> tag is a string that represents the ps auxw | grep -i [C]alendar.app command for better identification.

• The value 120 in the <frequency> tag specifies the command runs every 120 seconds (2 minutes).

Restart the Wazuh agent service to apply the changes:

# /Library/Ossec/bin/wazuh-control restart

Add the following rules to the /var/ossec/etc/rules/local_rules.xml file on the Wazuh server. The rule only matches the string ossec: output: 'check_calendar_status' in the command output as only one log is generated from the Logcollector configuration specified above:

<group name="process_monitor,">
  <rule id="100013" level="6">
    <if_sid>530</if_sid>
    <match>^ossec: output: 'check_calendar_status'</match>
    <description>Calendar is running.</description>
  </rule>
</group>

Restart the Wazuh manager to apply the changes:

$ sudo systemctl restart wazuh-manager