localfile

This configuration section is used to configure the collection of log data from files, Windows events, and from the output of commands.

Options

location

Option to get the location of a log or a group of logs. strftime format strings may be used for log file names.

For instance, a log file named file.log-2019-07-30 can be referenced with file.log-%Y-%m-%d (assuming today is July 30th, 2019).

Wildcards can be used on Linux and Windows systems, if the log file doesn't exist at wazuh-logcollector start time, such log will be re-scanned after logcollector.vcheck_files seconds.

The location field is also valid to filter by channel in case of using an eventchannel supporting Windows.

In the following example we can see two configurations showing a channel filtering for firewall and Sysmon events.

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

<localfile>
    <location>Microsoft-Windows-Windows Firewall With Advanced Security/Firewall</location>
    <log_format>eventchannel</log_format>
</localfile>

Below we have some Windows wildcard examples.

<localfile>
    <location>C:\Users\wazuh\myapp\*</location>
    <log_format>syslog</log_format>
</localfile>

<localfile>
    <location>C:\xampp\apache\logs\*.log</location>
    <log_format>syslog</log_format>
</localfile>

<localfile>
    <location>C:\logs\file-%Y-%m-%d.log</location>
    <log_format>syslog</log_format>
</localfile>

Default value

n/a

Allowed values

Any log file or wildcard

Note

  • strftime format strings and wildcards cannot be used on the same entry.

  • On Windows systems, only character * is supported as a wildcard. For instance *ANY_STRING*, will match all files that have ANY_STRING inside its name, another example is *.log this will match any log file.

  • The maximum amount of files monitored at same time is limited to 1000.

Warning

  • If using macos as log_format, then location must be set to macos as well.

command

Given a command output, it will be read as one or more log messages depending on command or full_command is used.

Default value

n/a

Allowed values

Any command line, optionally including arguments

alias

Change a command name in the log message.

For example <alias>usb-check</alias> would replace:

ossec: output: 'reg QUERY HKLM\SYSTEM\CurrentControlSet\Enum\USBSTOR':

with:

ossec: output: 'usb-check':

Default value

n/a

Allowed values

any string

frequency

Prevents a command from being executed in less time than the specified time (in seconds). This options can be used with command and full_command.

Default value

n/a

Allowed values

any positive number of seconds

only-future-events

It allows to read new log content since wazuh-logcollector was stopped.

By default, when wazuh-logcollector is started it reads the logs generated since that moment. Set it to no to collect events generated since wazuh-logcollector was stopped.

Default value

yes

Allowed values

yes or no

The attributes below are optional.

Attribute

Description

Value range

Default value

max-size

Allows to skip reading old events from the last read if the length of them exceeds a certain value in bytes.

Positive number followed by B, KB, MB and GB units are supported

0 to 2GB

10MB

Warning

If collecting logs with <log_format> set as macos, then max-size is ignored.

Note

If the log rotates while wazuh-logcollector is stopped and only-future-events is set to no, it will start reading from the beginning of the log.

query

This label can be used to filter Windows eventchannel events or macOS ULS logs (macos) that Wazuh will process.

To filter Windows eventchannel events, XPATH format is used to make the queries following the event schema.

Example:

<localfile>
  <location>Security</location>
  <log_format>eventchannel</log_format>
  <query>Event[System/EventID = 4624 and (EventData/Data[@Name='LogonType'] = 2 or EventData/Data[@Name='LogonType'] = 10)]</query>
</localfile>

To filter macOS ULS logs (macos), Predicates format is used to make the queries.

Example:

<localfile>
  <location>macos</location>
  <log_format>macos</log_format>
  <query type="log,trace" level="debug">process == "sshd" OR message CONTAINS "invalid"</query>
</localfile>

Default value

n/a

Allowed values

Windows Eventchannel

XPATH query format, follows the event schema

macOS ULS

Predicate query format, see How to collect macOS ULS logs

The attributes below are optional and only valid for macOS ULS (macos).

Attribute

Description

Value range

Default value

level

Indicates the level of verbosity, default is the less verbose and debug is the most verbose.

default

default

info

debug

type

Limits the type of logs that are intended to be acquired to the ones listed and sepparated by commas.

activity

all

log

trace

label

Used to add custom data in JSON events. Set log_format to json to use it.

Labels can be nested in JSON alerts by separating the "key" terms by a period.

Here is an example of how to identify the source of each log entry when monitoring several files simultaneously:

<localfile>
  <location>/var/log/myapp/log.json</location>
  <log_format>json</log_format>
  <label key="@source">myapp</label>
  <label key="agent.type">webserver</label>
</localfile>

This is a sample JSON object from the log file:

{
  "event": {
    "type": "write",
    "destination": "sample.txt"
  },
  "agent": {
    "name": "web01"
  }
}

The additional fields configured above would appear in the resulting event as below:

{
  "event": {
    "type": "write",
    "destination": "sample.txt"
  },
  "agent": {
    "name": "web01",
    "type": "webserver"
  },
  "@source": "myapp"
}

Note

If a label key already exists in the log data, the configured field value will not be included. It is recommended that a unique label key is defined by using a symbol prior to the key name as in @source.

target

Target specifies the name of the socket where the output will be redirected. The socket must be defined previously.

Default value

agent

Allowed values

any defined socket

log_format

Set the format of the log to be read. field is required

Note

For most of the text log files that only have one entry per line, syslog may be used.

Default value

n/a

Allowed values

syslog

Used for plain text files in a syslog-like format.

json

Used for single-line JSON files and allows for customized labels to be added to JSON events.

See also the tag label for more information.

snort-full

Used for Snort’s full-output format.

squid

Used for squid logs.

eventlog

Used for the classic Microsoft Windows event log format.

eventchannel

Used for Microsoft Windows event logs, gets the events in JSON format.

Monitors every channel specified in the configuration file and shows every field included in it.

This can be used to monitor standard “Windows” event logs and "Application and Services" logs.

macos

Used for macOS ULS logs, gets the logs in syslog format.

Monitors all the logs that match the query filter. See How to collect macOS ULS logs.

audit

Used for events from Auditd.

This format chains consecutive logs with the same ID into a single event.

mysql_log

Used for MySQL logs, however, this value does not support multi-line logs.

postgresql_log

Used for PostgreSQL logs, however, this value does not support multi-line logs.

nmapg

Used for monitoring files conforming to the grep-able output from nmap.

iis

Used for iis (Windows Web Server) logs.

command

Used to read the output from the command (as run by root) specified by the command tag.

Each line of output is treated as a separate log.

full_command

Used to read the output from the command (as run by root) specified by the command tag.

The entire output will be treated as a single log item.

djb-multilog

Used to read files in the format produced by the multi-log service logger in daemon tools.

multi-line

Used to monitor applications that log multiple lines per event.

The number of lines must be consistent in order to use this value.

The number of lines in each log entry must be specified following the multi-line: value.

Each line will be combined with the previous lines until all lines are gathered which means there

may be multiple timestamps in the final event.

The format for this value is: <log_format>multi-line: NUMBER</log_format>

multi-line-regex

Used to monitor applications that log variable amount lines with variable length per event.

The behavior depends on multiline_regex option.

Warning

Only one configuration block with log_format set as macos is allowed. If more blocks are added, the last one will be used.

Warning

The eventchannel log format cannot be used on Windows agents prior to the Vista OS as they do not produce this type of log.

Warning

Agents will ignore command and full_command log sources unless they have logcollector.remote_commands=1 set in their /var/ossec/etc/internal_options.conf or /var/ossec/etc/local_internal_options.conf file. This is a security precaution to prevent the Wazuh manager from running arbitrary commands on agents in their root security context.

Sample of Multi-line log message in original log file:

Aug 9 14:22:47 hostname log line one
Aug 9 14:22:47 hostname log line two
Aug 9 14:22:47 hostname log line four
Aug 9 14:22:47 hostname log line three
Aug 9 14:22:47 hostname log line five

Sample Log message as analyzed by wazuh-analysisd:

Aug 9 14:22:47 hostname log line one Aug 9 14:22:47 hostname log line two Aug 9 14:22:47 hostname log line three Aug 9 14:22:47 hostname log line four Aug 9 14:22:47 hostname log line five

out_format

This option allows formatting logs from Logcollector using field substitution.

The list of available parameters is:

Parameter

Description

log

Message from the log.

json_escaped_log

Message from the log, escaping JSON reserver characters.

base64_log

Message from the log, encoded in base64.

output

Output from a command. Alias of log.

location

Path to the source log file.

command

Command line or alias defined for the command. Alias of location.

timestamp

Current timestamp (when the log is sent), in RFC3164 format.

timestamp <format>

Custom timestamp, in strftime string format.

hostname

System's host name.

host_ip

Host's primary IP address.

Attributes:

target

This option selects a defined target to apply the output format.

Allowed values

Any target defined in the option <target>.

Default value

Select all targets defined in the <localfile> stanza.

ignore_binaries

This specifies to ignore binary files, testing if the file is UTF8 or ASCII.

If this is set to yes and the file is, for example, a binary file, it will be discarded.

Default value

n/a

Allowed values

yes or no

<localfile>
    <log_format>syslog</log_format>
    <location>/var/logs/*</location>
    <ignore_binaries>yes</ignore_binaries>
</localfile>

Note

On Windows agents, it will also check if the file is encoded with UCS-2 LE BOM or UCS-2 BE BOM.

age

This specifies to read-only files that have been modified before the specified age.

For example, if the age is set to 1 day, all files that have not been modified since 1 day will be ignored.

<localfile>
    <log_format>syslog</log_format>
    <location>/var/logs/*</location>
    <age>1d</age>
</localfile>

Default value

n/a

Allowed values

A positive number that should contain a suffix character indicating a time unit, such as, s (seconds), m (minutes), h (hours), d (days).

exclude

This indicates the location of a wild-carded group of logs to be excluded.

For example, we may want to read all the files from a directory, but exclude those files whose name starts with an e.

<localfile>
    <log_format>syslog</log_format>
    <location>/var/logs/*</location>
    <exclude>/var/logs/e*</exclude>
</localfile>

Default value

n/a

Allowed values

Any log file or wildcard

reconnect_time

Defines the interval of reconnection attempts when the Windows Event Channel service is down.

Default value

5s

Allowed values

A positive number that should contain a suffix character indicating a time unit, such as, s (seconds), m (minutes), h (hours), d (days), w (weeks)

Note

This option only applies when the log_format is eventchannel.

multiline_regex

This specifies a regular expression, match criteria and replace option for logs with a variable amount of lines.

Default value

n/a

Allowed values

Any PCRE2 regular expression

The attributes below are optional.

Attribute

Description

Value range

Default value

match

Allows to set how regex will handle regex match.

start

start

end

all

replace

Allows to replace or remove end-of-line.

no-replace

no-replace

wspace

tab

none

timeout

Allows to set max waiting time in seconds to receive a new line

1 to 120

5

Note

This option only applies when the log_format is multi-line-regex.

Note

The value of timeout attribute cannot be bigger than the value of the age option.

The behavior of the match attribute is as follows

Match

Description

start

Group as one event the content between two lines that matches the regex.

The grouped event does not include the last matching line.

end

Group as one event the content until a line that matches the regex.

all

Group as one event the content until whole event match the regex.

Note

start and end value for match attribute try to match the regex with a single line.

For example, we may want to read a Python Traceback output as one single log, replacing newline with spaces

<localfile>
    <log_format>multi-line-regex</log_format>
    <location>/var/logs/my_python_app.log</location>
    <multiline_regex replace="wspace">^Traceback</multiline_regex>
 </localfile>

ignore

Specify a regular expression to ignore log lines or command outputs when matching. Whether several ignore labels are defined, entries are ignored when matching any of the specified ones.

Default Value

n/a

Allowed values

Any regex, sregex or PCRE2 expression.

Use the type attribute to define the regular expression type. By default, PCRE2 is applied.

type

Allows to set regular expression type

Default value

PCRE2

Allowed values

osregex, osmatch, PCRE2

For example, to ignore events related to configuration changes in the audit log:

<localfile>
    <log_format>audit</log_format>
    <location>/var/log/audit/audit.log</location>
    <ignore type="PCRE2">type=.+_CHANGE</ignore>
    <ignore type="osregex">type=CONFIG_\.+</ignore>
</localfile>

restrict

Specify a regular expression to restrict processed log lines or command outputs. Whether several restrict labels are defined, entries are processed when matching all of them.

Default Value

n/a

Allowed values

Any regex, sregex or PCRE2 expression.

Use the type attribute to define the regular expression type. By default, PCRE2 is applied.

type

Allows to set regular expression type

Default value

PCRE2

Allowed values

osregex, osmatch, PCRE2

For example, to restrict syslog events related to a particular user name:

<localfile>
    <log_format>syslog</log_format>
    <location>/custom/file/path</location>
    <restrict type="PCRE2">username_\d?</restrict>
    <restrict type="osregex">Jun\.+</restrict>
</localfile>

Note

For formats that group multiple lines, the entire group is treated as a single log when evaluating the regex.

Note

Whether the same log entry matches an ignore and also a restrict configured for the same localfile, the entry is discarded. In other words, the ignore has precedence over restrict. Said that, if the same expression is defined in both ignore and restrict, no log will be processed for that localfile.

Note

The eventchannel format already provides a way to filter logs through queries. Therefore, ignore and restrict settings don't apply to this format.

Configuration examples

Linux configuration:

<!-- For monitoring log files -->
<localfile>
  <log_format>syslog</log_format>
  <location>/var/log/syslog</location>
</localfile>

<!-- For monitoring command output -->
<localfile>
  <log_format>command</log_format>
  <command>df -P</command>
  <frequency>360</frequency>
</localfile>

<!-- To use a custom target or format -->
<localfile>
  <log_format>syslog</log_format>
  <location>/var/log/auth.log</location>
  <target>agent,custom_socket</target>
  <out_format target="custom_socket">$(timestamp %Y-%m-%d %H:%M:%S): $(log)</out_format>
</localfile>

Windows configuration:

<!-- For monitoring Windows eventchannel -->
<localfile>
  <location>Security</location>
  <log_format>eventchannel</log_format>
  <only-future-events>yes</only-future-events>
  <query>Event/System[EventID != 5145 and EventID != 5156]</query>
  <reconnect_time>10s</reconnect_time>
</localfile>

macOS configuration:

<!-- For monitoring macOS ULS Logs -->
<localfile>
  <location>macos</location>
  <log_format>macos</log_format>
  <query type="trace,log,activity" level="info">process == "sshd" OR message CONTAINS "invalid"</query>
</localfile>