RULE - Administrator Guide - Cortex XSIAM - Cortex - Security Operations

Cortex XSIAM Documentation
Product
Cortex XSIAM
Creation date
2024-03-06
Last date published
2024-10-07
Category
Administrator Guide
Abstract

Learn how to write a RULE section in a Data Model Rules file and about the syntax to use in the file.

Rules are very similar to functions in modern programming languages. They are essentially named pieces of Cortex Query Language (XQL) syntax, and can be reused in the code in the MODEL sections, or in other RULE sections (recursively), by using [rule:ruleName]. A RULE is an optional data model syntax.

RULE syntax is derived from XQL with a few modifications, as explained in the Data Model Rules file structure and syntax.

Note

For more information on the XQL syntax, see the XQL Language Reference Guide.

Points to keep in mind when writing RULE sections

  • Rules are defined by [rule:ruleName] as shown in the following example:

    Example 97. 
    [RULE: common_ngfw_modeling]
alter xdm.source.ipv4 = json_extract_scalar(actor, "$.client_ip")
| alter xdm.network.ip_protocol = if(
	proto = 6, XDM_CONST.IP_PROTOCOL_TCP,
	proto = 11, XDM_CONST.IP_PROTOCOL_UDP,
	proto
);

  • Rules are invoked by using a call stage.

  • Rule names are not case-sensitive.

  • Rule names must be unique across the entire file.

  • As section order is not significant, you do not have to declare a rule before using it. You can have the rule definition section written below other sections that use that specific rule.

  • Each field used in the MODEL and RULE sections is constructed using dot notation with a specific format. However, temporary variables, which will not affect the modeling, can be used. For more information, see Field structure.