CONST - Administrator Guide - Cortex XSIAM - Cortex - Security Operations

Cortex XSIAM Administrator Guide

Product
Cortex XSIAM
Creation date
2024-02-26
Last date published
2024-05-12
Category
Administrator Guide
Abstract

Understanding how to write a [CONST] section in a Parsing Rules file and the syntax to use.

A CONST section is used to define strings and numbers that can be reused multiple times within Cortex Query Language (XQL) statements in other INGEST sections by using $constName. This can be helpful to avoid writing the same value in multiple sections, similar to constants in modern programming languages.

For example:

[CONST]
DEFAULT_DEVICE_NAME = "firewall3060";       // string
FILE_REGEX = "c:\\users\\[a-zA-Z0-9.]*";    // complex string
my_num = 3;                                 /* int */

An example of using a CONST inside XQL statements in other INGEST sections using $constName:

Note

The dollar sign ($) must be adjacent to the [CONST] name, without any whitespace in between.

...
| filter device_name = $DEFAULT_DEVICE_NAME
| alter new_field = JSON_EXTRACT(field, $FILE_REGEX)
| filter age < $MAX_TIMEOUT
| join type=$DEFAULT_JOIN_TYPE conflict_strategy=$DEFAULT_JOIN_CONFLICT_STRATEGY (dataset=my_lookup) as inn url=inn.url
...

NOTICE: Only quoted or integer terminal values are considered valid for CONST sections. For example, these will not compile:

[CONST]
WORD_CONST = abcde;                             //invalid
func_val = regex_extract(_raw_log, "regex");    // not possible
RECURSIVE_CONST = $WORD_CONST;                  // not terminal - not possible

CONST sections are meant to replace values. Other types, such as column names, are not supported:

...
| filter $DEVICE_NAME = "my_device"             // illegal
...

A few more points to keep in mind when writing CONST sections.

  • CONST names are not case-sensitive. They can be written in any user-desired casing, such as UPPER_SNAKE, lower_snake, camelCase, and CamelCase. For example, MY_CONST=My_Const=my_const.

  • CONST names must be unique inside a section, and across all sections of the file. You cannot have the same CONST name defined again in the same section, or in any other CONST sections in the file.

  • Since section order is unimportant, you do not have to declare a CONST before using it. You can have the CONST section written below other sections that use those CONST sections.

  • A CONST is an add-on to the Parsing Rule syntax and is optional to configure.

  • CONST syntax is derived from XQL, but a few modifications as explained in the Parsing Rules syntax.