Enrichment in the normalizer

When creating event parsing rules in the normalizer settings window, on the Enrichment tab, you can configure the rules for adding extra data to the fields of the normalized event using enrichment rules. These enrichment rules are stored in the settings of the normalizer where they were created.

Enrichments are created by using the Add enrichment button. There can be more than one enrichment rule. You can delete enrichment rules by using the button. Extended event schema fields can be used for event enrichment.

Settings available in the enrichment rule settings block:

• Source kind (required)—drop-down list for selecting the type of enrichment. Depending on the selected type, you may see advanced settings that will also need to be completed.

  Available Enrichment rule source types:

  • constant

    This type of enrichment is used when a constant needs to be added to an event field. Settings of this type of enrichment:

    • In the Constant field, specify the value that should be added to the event field. The value may not be longer than 255 Unicode characters. If you leave this field blank, the existing event field value will be cleared.
    • In the Target field drop-down list, select the KUMA event field to which you want to write the data.

    If you are using the event enrichment functions for extended schema fields of "String", "Number", or "Float" type with a constant, the constant is added to the field.

    If you are using the event enrichment functions for extended schema fields of "Array of strings", "Array of numbers", or "Array of floats" type with a constant, the constant is added to the elements of the array.

  • dictionary

    This type of enrichment is used if you need to add a value from the dictionary of the Dictionary type.

    When this type is selected in the Dictionary name drop-down list, you must select the dictionary that will provide the values. In the Key fields settings block, you must use the Add field button to select the event fields whose values will be used for dictionary entry selection.

    If you are using event enrichment with the "Dictionary" type selected as the "Source kind" setting, and an array field is specified in the "Key enrichment fields" setting, when an array is passed as the dictionary key, the array is serialized into a string in accordance with the rules of serializing a single value in the TSV format.

    Example: The "Key enrichment fields" setting uses the SA.StringArrayOne extended schema field. The SA.StringArrayOne extended schema field contains 3 elements: "a", "b" and "c". The following value is passed to the dictionary as the key: ['a','b','c'].

    If the "Key enrichment fields" setting uses an extended schema array field and a regular event schema field, the field values are separated by the "|" character when the dictionary is queried.

    Example: The "Key enrichment fields" setting uses two fields: the SA.StringArrayOne extended schema field and the Code field. The SA.StringArrayOne extended schema field contains 3 elements: "a", "b", and "c"; the Code string field contains the character sequence "myCode". The following value is passed to the dictionary as the key: ['a','b','c']|myCode.

  • table

    This type of enrichment is used if you need to add a value from the dictionary of the Table type.

    When this enrichment type is selected in the Dictionary name drop-down list, select the dictionary for providing the values. In the Key fields group of settings, use the Add field button to select the event fields whose values are used for dictionary entry selection.

    In the Mapping table, configure the dictionary fields to provide data and the event fields to receive data:

    • In the Dictionary field column, select the dictionary field. The available fields depend on the selected dictionary resource.
    • In the KUMA field column, select the event field to which the value is written. For some of the selected fields (*custom* and *flex*), in the Label column, you can specify a name for the data written to them.

    New table rows can be added by using the Add new element button. Columns can be deleted using the button.

  • event

    This type of enrichment is used when you need to write a value from another event field to the current event field. Settings of this type of enrichment:

    • In the Target field drop-down list, select the KUMA event field to which you want to write the data.
    • In the Source field drop-down list, select the event field whose value will be written to the target field.
    • Clicking the button opens the Conversion window in which you can, using the Add conversion button, create rules for modifying the original data before writing them to the KUMA event fields.

      Available conversions

      Conversions are changes that can be applied to a value before it gets written to the event field. The conversion type is selected from a drop-down list.

      Available conversions:

      • lower—is used to make all characters of the value lowercase
      • upper—is used to make all characters of the value uppercase
      • regexp – used to convert a value using the regular expression RE2. When this conversion type is selected, the field appears where regular expression should be added.
      • substring—is used to extract characters in the position range specified in the Start and End fields. These fields appear when this conversion type is selected.
      • replace—is used to replace specified character sequence with the other character sequence. When this type of conversion is selected, new fields appear:
        • Replace chars—in this field you can specify the character sequence that should be replaced.
        • With chars—in this field you can specify the characters sequence should be used instead of replaced characters.
      • trim—used to simultaneously remove the characters specified in the Chars field from the leading and end positions of the value. The field appears when this type of conversion is selected. For example, a trim conversion with the Micromon value applied to Microsoft-Windows-Sysmon results in soft-Windows-Sys.
      • append is used to add the characters specified in the Constant field to the end of the event field value. The field appears when this type of conversion is selected.
      • prepend—used to prepend the characters specified in the Constant field to the start of the event field value. The field appears when this type of conversion is selected.
      • replace with regexp—is used to replace RE2 regular expression results with the character sequence.
        • Expression—in this field you can specify the regular expression which results that should be replaced.
        • With chars—in this field you can specify the characters sequence should be used instead of replaced characters.
      • Converting encoded strings to text:
        • decodeHexString—used to convert a HEX string to text.
        • decodeBase64String—used to convert a Base64 string to text.
        • decodeBase64URLString—used to convert a Base64url string to text.

        When converting a corrupted string or if conversion error occur, corrupted data may be written to the event field.

        During event enrichment, if the length of the encoded string exceeds the size of the field of the normalized event, the string is truncated and is not decoded.

        If the length of the decoded string exceeds the size of the event field into which the decoded value is to be written, such a string is truncated to fit the size of the event field.

      Conversions when using the extended event schema

      Whether or not a conversion can be used depends on the type of extended event schema field being used:

      • For an additional field of the "String" type, all types of conversions are available.
      • For fields of the "Number" and "Float" types, the following types of conversions are available: regexp, substring, replace, trim, append, prepend, replaceWithRegexp, decodeHexString, decodeBase64String, decodeBase64URLString.
      • For fields of "Array of strings", "Array of numbers", and "Array of floats" types, the following types of conversions are available: append, prepend.

    When using enrichment of events that have the "Event" selected as the "Source kind" setting and the fields of the extended event schema are used as arguments, the following special considerations apply:

    • If the source field is an "Array of strings" field and the target field is a "String" field, the values are written to the target field in the TSV format.

      Example: The SA.StringArray extended event schema field contains values: "string1", "string2", "string3". An event enrichment operation is performed. The result of the operation is written to the DeviceCustomString1 event schema field. As a result of the operation, the DeviceCustomString1 field contains ["string1", "string2", "string3"].

    • If the source field is an "Array of strings" field and the target field is an "Array of strings" field, the values are written to the target field, and commas (",") are used as the separator character.

      Example: The SA.StringArrayOne extended event schema field contains values: "string1", "string2", "string3". An event enrichment operation is performed. The result of the operation is written to the SA.StringArrayTwo event schema field. As a result of the operation, the SA.StringArrayTwo field contains "string1", "string2", "string3".

  • template

    This type of enrichment is used when you need to write a value obtained by processing Go templates into the event field. Settings of this type of enrichment:

    • Put the Go template into the Template field.

      Event field names are passed in the {{.EventField}} format, where EventField is the name of the event field from which the value must be passed to the script.

      Example: Attack on {{.DestinationAddress}} from {{.SourceAddress}}.

    • In the Target field drop-down list, select the KUMA event field to which you want to write the data.

    If you are using enrichment of events that have the "Template" type selected as the "Source kind" setting, in which the target field has the "String" type, and the source field is an extended event schema field containing an array of strings, you can use one of the following examples for the template.

    Example:

    {{.SA.StringArrayOne}}

    Example:

    {{- range $index, $element := . SA.StringArrayOne -}}

    {{- if $index}}, {{end}}"{{$element}}"{{- end -}}

• Target field (required)—drop-down list for selecting the KUMA event field that should receive the data.

  This setting is not available for the enrichment source of the Table type.

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