Rules Syntax¶

Available options¶

rule¶

level	Definition	Specifies the level of the rule. Alerts and responses use this value.
level	Allowed values	0 to 16
id	Definition	Specifies the ID of the rule.
id	Allowed values	Any number from 1 to 999999
maxsize	Definition	Specifies the maximum size of the event.
maxsize	Allowed values	Any number from 1 to 9999
frequency	Definition	Number of times the rule must have matched before firing.
frequency	Allowed values	Any number from 2 to 9999
timeframe	Definition	The timeframe in seconds. This option is intended to be used with the frequency option.
timeframe	Allowed values	Any number from 1 to 99999
ignore	Definition	The time (in seconds) to ignore this rule after firing it (to avoid floods).
ignore	Allowed values	Any number from 1 to 999999
overwrite	Definition	Used to supersede an OSSEC rule with local changes.
overwrite	Allowed values	yes, no
noalert	Definition	Not trigger any alert if the rule matches.
noalert	Allowed values	Attribute with no value

match¶

Any string to match against the log event.

Default Value	n/a
Allowed values	Any sregex expression

regex¶

Any regex to match against the log event.

Default Value	n/a
Allowed values	Any regex expression

decoded_as¶

Default Value	n/a
Allowed values	Any decoder name

category¶

The decoded category to match: ids, syslog, firewall, web-log, squid or windows.

Default Value	n/a
Allowed values	Any category

field¶

Any regex to be compared to a field extracted by the decoder.

name

Specifies the name of the field extracted by the decoder.

srcip¶

Any IP address or CIDR block to be compared to an IP decoded as srcip. Use “!” to negate it.

Default Value	n/a
Allowed values	Any srcip

dstip¶

Any IP address or CIDR block to be compared to an IP decoded as dstip. Use “!” to negate it.

Default Value	n/a
Allowed values	Any dstip

extra_data¶

Any string that is decoded into the extra_data field.

Default Value	n/a
Allowed values	Any string.

user¶

Any username (decoded as the username).

Default Value	n/a
Allowed values	Any sregex expression

program_name¶

Program name is decoded from syslog process name.

Default Value	n/a
Allowed values	Any sregex expression

hostname¶

Any hostname (decoded as the syslog hostname) or log file.

Default Value	n/a
Allowed values	Any sregex expression

time¶

Time that the event was generated.

Default Value	n/a
Allowed values	Any time range (hh:mm-hh:mm)

weekday¶

Week day that the event was generated.

Default Value	n/a
Allowed values	monday - sunday, weekdays, weekends

id¶

Any ID (decoded as the ID).

Default Value	n/a
Allowed values	Any sregex expression

url¶

Any URL (decoded as the URL).

Default Value	n/a
Allowed values	Any sregex expression

action¶

Any action (decoded as the ACTION).

Default Value	n/a
Allowed values	Any String.

if_sid¶

Matches if the ID has matched.

Default Value	n/a
Allowed values	Any rule id

if_group¶

Matches if the group has matched before.

Default Value	n/a
Allowed values	Any Group

if_level¶

Matches if the level has matched before.

Default Value	n/a
Allowed values	Any level from 1 to 16

if_matched_sid¶

Matches if an alert of the defined ID has been triggered in a set number of seconds.

This option is used in conjunction with frequency and timeframe.

Default Value	n/a
Allowed values	Any rule id

Note

Rules at level 0 are discarded immediately and will not be used with the if_matched_rules. The level must be at least 1, but the <no_log> option can be added to the rule to make sure it does not get logged.

if_matched_group¶

Matches if an alert of the defined group has been triggered in a set number of seconds.

This option is used in conjunction with frequency and timeframe.

Default Value	n/a
Allowed values	Any Group

same_id¶

Specifies that the decoded id must be the same. This option is used in conjunction with frequency and timeframe.

Example of use

<same_id />

same_source_ip¶

Specifies that the decoded source ip must be the same. This option is used in conjunction with frequency and timeframe.

Example of use

<same_source_ip />

same_src_port¶

Specifies that the decoded source port must be the same. This option is used in conjunction with frequency and timeframe.

Example of use

<same_src_port />

same_dst_port¶

Specifies that the decoded destination port must be the same. This option is used in conjunction with frequency and timeframe.

Example of use

<same_dst_port />

same_location¶

Specifies that the location must be the same. This option is used in conjunction with frequency and timeframe.

Example of use

<same_location />

same_user¶

Specifies that the decoded user must be the same. This option is used in conjunction with frequency and timeframe.

Example of use

<same_user />

different_url¶

Specifies that the decoded url must be different. This option is used in conjunction with frequency and timeframe.

Example of use

<different_url />

different_srcgeoip¶

Specifies that the source geoip location must be different. This option is used in conjunction with frequency and timeframe.

Example of use

<different_srcgeoip />

description¶

Rule description.

Default Value	n/a
Allowed values	Any string

Since Wazuh v3.3.0 it is possible to include any decoded field (static or dynamic) to the description message.

list¶

Perform a CDB lookup using an ossec list. This is a fast on disk database which will always find keys within two seeks of the file.

Default Value	n/a
Allowed values	Path to the CDB file to be used for lookup from the OSSEC directory.Must also be included in the ossec.conf file.

Attribute	Description
field	key in the CDB: srcip, srcport, dstip, dstport, extra_data, user, url, id, hostname, program_name, status, action, dynamic field.
lookup	match_key	key to search within the cdb and will match if they key is present. Default.
	not_match_key	key to search and will match if it is not present in the database.
	match_key_value	searched for in the cdb. It will be compared with regex from attribute check_value.
	address_match_key	IP and the key to search within the cdb and will match if they key is present.
	not_address_match_key	IP the key to search and will match if it IS NOT present in the database
	address_match_key_value	IP to search in the cdb. It will be compared with regex from attribute check_value.
check_value	regex for matching on the value pulled out of the cdb when using types: address_match_key_value, match_key_value

info¶

Extra information may be added through the following attributes:

Default Value	n/a
Allowed values	Any string

Attribute	Allowed values	Description
type	text	This is the default when no type is selected. Additional,information about the alert/event.
	link	Link to more information about the alert/event.
	cve	The CVE Number related to this alert/event.
	ovsdb	The osvdb id related to this alert/event.

options¶

Additional rule options

Attribute	Description
alert_by_email	Always alert by email.
no_email_alert	Never alert by email.
no_log	Do not log this alert.
no_full_log	Do not include the `full_log` field in the alert.
no_counter	Omit field `rule.firedtimes` in the JSON alert.

Note

Use one <options> tag for each option you want to add.

check_diff¶

Used to determine when the output of a command changes.

Example of use

<check_diff />

group¶

Add additional groups to the alert. Groups are optional tags added to alerts.

They can be used by other rules by using if_group or if_matched_group, or by alert parsing tools to categorize alerts.

Default Value	n/a
Allowed values	Any String