Alert management

Configuration

Syslog output is configured in the Wazuh server /var/ossec/etc/ossec.conf configuration file within the <ossec_config> block. By default, the Wazuh manager forwards alerts to syslog servers using port 514 via the UDP protocol.

The code block below shows a sample configuration to forward alerts to a syslog server:

<ossec_config>
  <syslog_output>
    <level>9</level>
    <server>192.168.1.241</server>
  </syslog_output>
</ossec_config>

The configuration options are defined as follows:

• The <level> tag sets the minimum severity level of the alerts to be forwarded to the syslog server. The example value 9 indicates the Wazuh server only forwards alerts to the syslog server if the alert level is higher than 9. If this option is not defined, the Wazuh server forwards all alerts to the syslog server.

• The <server> tag sets the IP address or hostname of the syslog server to forward the alerts. The IP address 192.168.1.241 in the configuration is used as an example.

You can learn more about the available configuration options in the syslog_output reference guide.

Restart the Wazuh manager service to apply the changes after every configuration:

# systemctl restart wazuh-manager

# service wazuh-manager restart

You can also forward alerts to multiple syslog servers by defining multiple <syslog_output> blocks within the <ossec_config> block in the /var/ossec/etc/ossec.conf configuration file.

<ossec_config>
  <syslog_output>
    <server>192.168.1.240</server>
  </syslog_output>

  <syslog_output>
    <level>9</level>
    <server>192.168.1.241</server>
  </syslog_output>
</ossec_config>

In the configuration above,

• The first <syslog_output> block sends all alerts without filtering to the syslog server with IP address 192.168.1.240.

• The second <syslog_output> block sends alerts to the syslog server 192.168.1.241 only if the alert level is higher than 9.

Generic email options

To configure Wazuh to send email alerts, we configure the email options within the <global> section of the /var/ossec/etc/ossec.conf file.

A sample email configuration to send alerts to the email address me@test.com is shown below:

<ossec_config>
  <global>
    <email_notification>yes</email_notification>
    <email_to>me@test.com</email_to>
    <smtp_server>mail.test.com</smtp_server>
    <email_from>wazuh@test.com</email_from>
  </global>
  ...
</ossec_config>

Once the above has been configured, the email_alert_level option needs to be set to the minimum alert level to trigger an email. By default, this level is set to 12.

This example configuration below sets the minimum level to send email alerts to 10:

<ossec_config>
  <alerts>
    <email_alert_level>10</email_alert_level>
  </alerts>
  ...
</ossec_config>

For more information about the available email configuration options, see the global and alerts reference guides.

Restart the Wazuh manager service to apply the changes after every configuration:

# systemctl restart wazuh-manager

# service wazuh-manager restart

Granular email options

Wazuh allows granular configuration options for email alerts. This setting extends the generic email options configured in the <global> section of the /var/ossec/etc/ossec.conf file. Granular email configurations are defined within the <email_alerts> tag of the /var/ossec/etc/ossec.conf file.

Below are some sample granular configurations for sending alerts via email. For more information, see the email_alerts section.

<email_alerts>
  <email_to>you@example.com</email_to>
  <level>4</level>
  <do_not_delay/>
</email_alerts>

<email_alerts>
  <email_to>you@example.com</email_to>
  <event_location>server1</event_location>
  <do_not_delay/>
</email_alerts>

<email_alerts>
  <email_to>you@example.com</email_to>
  <rule_id>515, 516</rule_id>
  <do_not_delay/>
</email_alerts>

<email_alerts>
  <email_to>you@example.com</email_to>
  <group>pci_dss_10.6.1,</group>
</email_alerts>

<ossec_config>
  <email_alerts>
    <email_to>alice@test.com</email_to>
    <event_location>endpoint1|endpoint2</event_location>
  </email_alerts>

  <email_alerts>
    <email_to>is@test.com</email_to>
    <event_location>/log/secure$</event_location>
  </email_alerts>

  <email_alerts>
    <email_to>bob@test.com</email_to>
    <event_location>192.168.</event_location>
  </email_alerts>

  <email_alerts>
    <email_to>david@test.com</email_to>
    <level>12</level>
  </email_alerts>
</ossec_config>

Force forwarding an alert by email

The minimum severity level to send an alert via email is 12 by default. You can configure the Wazuh manager to forcefully send an email alert below the configured minimum severity level. To do so, you need to use one of the rule options below:

• alert_by_email to always alert by email.

• no_email_alert to never alert by email.

• no_log to not log this alert.

For example, the rule definition below sends an email every time rule 502 is triggered, regardless of what the minimum severity level is set to:

<rule id="502" level="3">
  <if_sid>500</if_sid>
  <options>alert_by_email</options>
  <match>Ossec started</match>
  <description>Ossec server started.</description>
</rule>

SMTP server with authentication

Wazuh email alerts do not support SMTP servers with authentication, such as Gmail. However, you can send these emails via a server relay like Postfix.

Perform the steps below on your relay server to configure Postfix with Gmail.

1. Run this command to install the required packages. Select No configuration, if prompted about the mail server configuration type.

   CentOSUbuntu

   # yum update && yum install postfix mailx cyrus-sasl cyrus-sasl-plain
   

2. Append these lines to the /etc/postfix/main.cf file to configure Postfix. Create the file if missing.

   CentOSUbuntu

   relayhost = [smtp.gmail.com]:587
   smtp_sasl_auth_enable = yes
   smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
   smtp_sasl_security_options = noanonymous
   smtp_tls_CAfile = /etc/ssl/certs/ca-bundle.crt
   smtp_use_tls = yes
   

3. Set the credentials of the sender in the /etc/postfix/sasl_passwd file and create a database file for Postfix. Replace the <USERNAME> and <PASSWORD> variables with sender’s email address username and password respectively.

   # echo [smtp.gmail.com]:587 <USERNAME>@gmail.com:<PASSWORD> > /etc/postfix/sasl_passwd
   # postmap /etc/postfix/sasl_passwd
   

   Note

   The password must be an App Password. App Passwords can only be used with accounts that have 2-Step Verification turned on.

4. Secure your password DB file so that only the root user has full read and write access to it. This is because the /etc/postfix/sasl_passwd and /etc/postfix/sasl_passwd.db files have plaintext credentials.

   # chown root:root /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
   # chmod 0600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
   

5. Restart Postfix to effect the configuration changes:

   SystemdSysV init

   # systemctl restart postfix
   

6. Run the following command to test the configuration:

   # echo "Test mail from postfix" | mail -s "Test Postfix" -r "<CONFIGURED_EMAIL>" <RECEIVER_EMAIL>
   

   Replace:

   • <CONFIGURED_EMAIL> with your configured email address.

   • <RECEIVER_EMAIL> with the email address of the recipient.

   The command sends an email to the receiver’s email with subject Test Postfix and body Test mail from postfix.

   If you get the error message fatal: tls_fprint: error computing md5 message digest in the /var/log/maillog file, run the following commands to switch Postfix from the default MD5 hashing function to SHA-256:

   # postconf -e smtp_tls_fingerprint_digest=sha256
   # postconf -e smtpd_tls_fingerprint_digest=sha256
   

7. Configure email notifications within the <global> tag of the Wazuh server’s /var/ossec/etc/ossec.conf file as follows:

   <global>
     <email_notification>yes</email_notification>
     <smtp_server>localhost</smtp_server>
     <email_from><USERNAME>@gmail.com</email_from>
     <email_to><RECEIVER_EMAIL></email_to>
   </global>
   

   Where:

   • <email_notification> toggles the use of email alerting.

   • <smtp_server> defines the SMTP server to use to deliver alerts.

   • <email_from> specifies the email address of the configured sender. Replace <USERNAME> with your configured username of your email address.

   • <email_to> specifies the email address of the recipient of alerts. Replace <RECEIVER_EMAIL> with the email address of the recipient.

8. Restart the Wazuh manager to apply the changes:

   SystemdSysV init

   # systemctl restart wazuh-manager
   

Prerequisites

You need to install the development libraries for the database system you want to configure and compile the Wazuh manager to use the required database system.

1. Install the development libraries for the database system:

   • For MySQL:

     YumAPT

     # yum install mysql-devel
     

   • For PostgreSQL:

     YumAPT

     # yum install postgresql-devel
     

2. Install the dependencies as outlined in the installing dependencies section.

3. Download and extract the latest version of Wazuh:

   # curl -Ls https://github.com/wazuh/wazuh/archive/v4.9.1.tar.gz | tar zx
   

4. Execute the following commands to switch to the Wazuh directory and specify the database type to use, replacing the <DATABASE_TYPE> variable with either mysql or pgsql:

   # cd wazuh-4.9.1/src
   # make deps && make TARGET=server DATABASE=<DATABASE_TYPE>
   

   Note

   Depending on your system specifications, the compilation process might take some time.

5. Run the install.sh script. It displays a wizard to guide you through the installation process using the Wazuh sources:

   # cd ..
   # ./install.sh
   

6. When the script asks what kind of installation you want, type manager to install the Wazuh manager:

   1- What kind of installation do you want (manager, agent, local, hybrid, or help)? manager
   

   Note

   During the installation, you can decide the installation path. Execute the install.sh and select the language, set the installation mode to manager, then set the installation path (Choose where to install Wazuh [/var/ossec]). The default path of installation is /var/ossec. A commonly used custom path might be /opt.

   Warning

   Be extremely careful not to select a critical installation directory if you choose a different path than the default. If the directory already exists, the installer will ask to delete the directory or proceed by installing Wazuh inside it.

7. The installer asks if you want to start Wazuh at the end of the installation. If you choose not to, you can start it later with the command below:

   SystemdSysV init

   # systemctl restart wazuh-manager
   

Database configuration

According to your database system, create a new database, set up the database user, and add the schema located in the src/os_dbd directory of the source code with the following commands:

• For MySQL:

  # mysql -u root -p
  

  mysql> CREATE DATABASE Alerts_DB;
  Query OK, 1 row affected (2.34 sec)
  
  mysql> CREATE USER '<DATABASE_USER>'@'<DATABASE_SERVER_IP>' IDENTIFIED BY '<DATABASE_USER_PASSWORD>';
  Query OK, 0 rows affected (0.00 sec)
  
  mysql> GRANT INSERT,SELECT,UPDATE,CREATE,DELETE,EXECUTE on Alerts_DB.* to '<DATABASE_USER>'@'<DATABASE_SERVER_IP>';
  Query OK, 0 rows affected (0.00 sec)
  
  mysql> FLUSH PRIVILEGES;
  Query OK, 0 rows affected (0.00 sec)
  
  mysql> quit;
  

  Replace the following variables in the commands above:

  • <DATABASE_USER> with the user you want to create for the database server.

  • <DATABASE_SERVER_IP> with the IP address of the database server.

  • <DATABASE_USER_PASSWORD> with the user password to access the database server.

  # mysql -u root -p Alerts_DB < src/os_dbd/mysql.schema
  

• For PostgreSQL:

  # sudo -u postgres createuser -P <DATABASE_USER>
  # sudo -u postgres createdb -O <DATABASE_USER> Alerts_DB
  # psql -U <DATABASE_USER> -d Alerts_DB -f src/os_dbd/postgresql.schema
  

  Replace <DATABASE_USER> with the user you want to create for the database server.

Wazuh manager configuration

Perform the following steps to configure the Wazuh manager to send alerts and other data to the database system.

1. Add the following block of code within the <ossec_config> block of the /var/ossec/etc/ossec.conf file on the Wazuh server:

   • For MySQL:

     <database_output>
       <hostname><DATABASE_SERVER_IP></hostname>
       <username><DATABASE_USER></username>
       <password><DATABASE_USER_PASSWORD></password>
       <database>Alerts_DB</database>
       <type>mysql</type>
     </database_output>
     

   • For PostgreSQL:

     <database_output>
       <hostname><DATABASE_SERVER_IP></hostname>
       <username><DATABASE_USER></username>
       <password><DATABASE_USER_PASSWORD></password>
       <database>Alerts_DB</database>
       <type>postgresql</type>
     </database_output>
     

   Where:

   • <hostname> specifies the IP address of the database server. Replace <DATABASE_SERVER_IP> the IP address of the database server.

   • <username> specifies the user to access the database. Replace <DATABASE_USER> with the database user created above.

   • <password> specifies the user password to access the database. Replace <DATABASE_USER_PASSWORD> with the user password created above.

   • <database> specifies the name of the database in which to store the alerts. For example, Alerts_DB as specified in the configuration above.

   • <type> specifies the type of database (MySQL or PostgreSQL). The allowed values are mysql or pgsql.

   For more information on the database_output option, see the database_output section of the reference guide.

2. Restart the Wazuh manager service to apply the changes:

   SystemdSysV init

   # systemctl restart wazuh-manager
   

3. Run the command below to verify that the Wazuh manager is connected to the database:

   # grep wazuh-dbd /var/ossec/logs/ossec.log
   

   2024/06/24 14:49:11 wazuh-dbd: INFO: Connected to database 'Alerts_DB' at '127.0.0.1'.
   

The database will now start receiving data from the Wazuh manager.