How it works

Log files

The Log analysis engine can be configured to monitor specific files on the servers.

Sample Configuration:

Linux:

<localfile>
    <location>/var/log/example.log</location>
    <log_format>syslog</log_format>
</localfile>

Windows:

<localfile>
    <location>C:\myapp\example.log</location>
    <log_format>syslog</log_format>
</localfile>

Windows event logs

Wazuh can monitor classic Windows event logs, as well as the newer Windows event channels:

Sample configuration:

Event log:

<localfile>
  <location>Security</location>
  <log_format>eventlog</log_format>
</localfile>

Event channel:

<localfile>
  <location>Microsoft-Windows-PrintService/Operational</location>
  <log_format>eventchannel</log_format>
</localfile>

Remote syslog

On other devices, like firewalls, for instance, the log analysis component can be configured to receive log events through syslog.

Sample configuration:

<ossec_config>
  <remote>
    <connection>syslog</connection>
    <port>514</port>
    <protocol>udp</protocol>
    <allowed-ips>192.168.2.0/24</allowed-ips>
  </remote>
<ossec_config>

<connection>syslog</connection> indicates that the manager will accept incoming syslog messages from across the network and <allowed-ips>192.168.2.0/24</allowed-ips> defines the network from which syslog messages will be accepted.

Log example:

2016-03-15T15:22:10.078830+01:00 tron su:pam_unix(su-l:auth):authentication failure;logname=tm uid=500 euid=0 tty=pts/0 ruser=tm rhost= user=root
1265939281.764 1 172.16.167.228 TCP_DENIED /403 734 POST http://lbcore1.metacafe.com/test/SystemInfoManager.php - NONE/- text/html
[Sun Mar 06 08:52:16 2016] [error] [client 187.172.181.57] Invalid URI in request GET: index.php HTTP/1.0

If a /etc/rsyslog.conf configuration file is being used instead of the ossec.conf options as above, you can still analyze logs using a <localfile> block with syslog as the log format.

<localfile>
  <log_format>syslog</log_format>
  <location>/custom/file/path</location>
</localfile>

Pre-decoding

In the pre-decoding phase of analysis, static information from well-known fields all that is extracted from the log. data

Feb 14 12:19:04 localhost sshd[25474]: Accepted password for rromero from 192.168.1.133 port 49765 ssh2

Extracted information:

• hostname: 'localhost'

• program_name: 'sshd'

Decoding

In the decoding phase, the log message is evaluated to identify what type of log it is and known fields for that specific log type are then extracted.

Sample log and its extracted info:

Feb 14 12:19:04 localhost sshd[25474]: Accepted password for rromero from 192.168.1.133 port 49765 ssh2

Extracted information:

• program name: sshd

• dstuser: rromero

• srcip: 192.168.1.133

Rule matching

In the next phase, the extracted log information is compared to the ruleset to look for matches:

For the previous example, rule 5715 is matched:

<rule id="5715" level="3">
  <if_sid>5700</if_sid>
  <match>^Accepted|authenticated.$</match>
  <description>sshd: authentication success.</description>
  <group>authentication_success,pci_dss_10.2.5,</group>
</rule>