Response rules for a custom script

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Response rules

Response rules for a custom script

April 8, 2024

ID 233366

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You can create a script containing commands to be executed on the KUMA server when selected events are detected and configure response rules to automatically run this script. In this case, the program will run the script when it receives events that match the response rules.

The script file is stored on the server where the correlator service using the response resource is installed: /opt/kaspersky/kuma/correlator/<Correlator ID>/scripts. The kuma user of this server requires the permissions to run the script.

When creating and editing response rules for a custom script, you need to define values for the following parameters.

Response rule settings

Setting	Description
Name	Required setting. Unique name of the resource. Must contain 1 to 128 Unicode characters.
Tenant	Required setting. The name of the tenant that owns the resource.
Type	Required setting. Response rule type, script.
Timeout	The number of seconds allotted for the script to finish. If this amount of time is exceeded, the script is terminated.
Script name	Required setting. Name of the script file. If the response resource is attached to the correlator service but there is no script file in the /opt/kaspersky/kuma/correlator/<Correlator ID>/scripts folder, the correlator will not work.
Script arguments	Arguments or event field values that must be passed to the script. If the script includes actions taken on files, you should specify the absolute path to these files. Parameters can be written with quotation marks ("). Event field names are passed in the `{{.EventField}}` format, where `EventField` is the name of the event field which value must be passed to the script. Example: `-n "\"usr\": {{.SourceUserName}}"`
Handlers	The number of handlers that the service can run simultaneously to process response rules in parallel. By default, the number of handlers is the same as the number of virtual processors on the server where the service is installed.
Description	Description of the resource. You can add up to 4,000 Unicode characters.
Filter	Used to define the conditions for the events to be processed using the response rule. You can select an existing filter from the drop-down list or create a new filter. Creating a filter in resources In the Filter drop-down list, select Create new. If you want to keep the filter as a separate resource, select the Save filter check box. In this case, you will be able to use the created filter in various services. This check box is cleared by default. If you selected the Save filter check box, enter a name for the created filter resource in the Name field. The name must contain 1 to 128 Unicode characters. In the Conditions settings block, specify the conditions that the events must meet: Click the Add condition button. In the Left operand and Right operand drop-down lists, specify the search parameters. Depending on the data source selected in the Right operand field, you may see fields of additional parameters that you need to use to define the value that will be passed to the filter. For example, when choosing active list you will need to specify the name of the active list, the entry key, and the entry key field. In the operator drop-down list, select the relevant operator. Filter operators =—the left operand equals the right operand. <—the left operand is less than the right operand. <=—the left operand is less than or equal to the right operand. >—the left operand is greater than the right operand. >=—the left operand is greater than or equal to the right operand. inSubnet—the left operand (IP address) is in the subnet of the right operand (subnet). contains—the left operand contains values of the right operand. startsWith—the left operand starts with one of the values of the right operand. endsWith—the left operand ends with one of the values of the right operand. match—the left operand matches the regular expression of the right operand. The RE2 regular expressions are used. hasBit—checks whether the left operand (string or number) contains bits whose positions are listed in the right operand (in a constant or in a list). The value to be checked is converted to binary and processed right to left. Chars are checked whose index is specified as a constant or a list. If the value being checked is a string, then an attempt is made to convert it to integer and process it in the way described above. If the string cannot be converted to a number, the filter returns False. hasVulnerability—checks whether the left operand contains an asset with the vulnerability and vulnerability severity specified in the right operand. If you do not specify the ID and severity of the vulnerability, the filter is triggered if the asset in the event being checked has any vulnerability. inActiveList—this operator has only one operand. Its values are selected in the Key fields field and are compared with the entries in the active list selected from the Active List drop-down list. inDictionary—checks whether the specified dictionary contains an entry defined by the key composed with the concatenated values of the selected event fields. inCategory—the asset in the left operand is assigned at least one of the asset categories of the right operand. inActiveDirectoryGroup—the Active Directory account in the left operand belongs to one of the Active Directory groups in the right operand. TIDetect—this operator is used to find events using CyberTrace Threat Intelligence (TI) data. This operator can be used only on events that have completed enrichment with data from CyberTrace Threat Intelligence. In other words, it can only be used in collectors at the destination selection stage and in correlators. inContextTable—presence of the entry in the specified context table. intersect—presence in the left operand of the list items specified in the right operand. If necessary, select the do not match case check box. When this check box is selected, the operator ignores the case of the values. The selection of this check box does not apply to the InSubnet, InActiveList, InCategory or InActiveDirectoryGroup operators. This check box is cleared by default. If you want to add a negative condition, select If not from the If drop-down list. You can add multiple conditions or a group of conditions. If you have added multiple conditions or groups of conditions, choose a search condition (and, or, not) by clicking the AND button. If you want to add existing filters that are selected from the Select filter drop-down list, click the Add filter button. You can view the nested filter settings by clicking the button.

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