Generate alerts from indicators using indicator rules for prevention and detection - Threat Intel Management Guide - Cortex XSIAM - Cortex

Abstract

Create detection and prevention rules using threat intelligence as a source.

Indicator rules allow you to utilize indicators in the system for detection and prevention. These rules allow you to select indicators or indicator traits to be detected by the server and prevented by the endpoint. Indicator rules marked for detection and prevention generate alerts that you can then track and investigate.

Note

Indicators should be present in the TIM database (Detection & Threat Intel → Threat Intel Management → Indicators) before creating detection and prevention rules.

Indicator rules can be used for the following:

Real-time prevention on the agent
Create an indicator rule for a Restrictions profile on the Agent using filters applied on file (SHA256 and MD5) indicators. A Restrictions profile limits the locations from which executables can run on an endpoint. When the Cortex XDR agent detects behavior that matches a rule defined in your profile, the Cortex XDR agent applies the security profile that is attached to the rule for further inspection. An alert is then generated in Cortex XSIAM (source is XDR Agent). For more information about the Restrictions profile, see Set up Restrictions Security Profiles.
Server-side detection
Create rules based on filters that are applied to a file (SHA256, MD5) an IP address, and a domain. If an indicator rule applies, an alert is generated in Cortex XSIAM (source is Threat Intelligence).

Create a Prevention Rule

Prevention Rules are created based on the file (SHA256 and MD5) indicator type.

Create a Restrictions Profile.
1. Select Endpoints → Policy Management → Prevention → Profiles → Add Profile → Create New.
2. Select one of the following Platforms.
  - Windows
  - MacOS
  - Linx
3. Select Restrictions.
4. From the Custom Indicator Prevention Rules section, in the Action Mode field, select Enabled.
  You will see that there are no custom prevention rules defined. After you create an indicator rule you will need to edit this profile and select the indicator rule.
5. Add the parameters as required. For more information, see Set up Restrictions Security Profiles.
6. Create the Profile.

Create the Indicator Rule.

Select Detection & Threat Intel → Threat Intel Management → Indicator Rules → Add Rule → Prevention Rule.

From the Create New Prevention Rule wizard, in the General section, add the following parameters:

Parameter	Description
Rule Name	Add a meaningful name.
Select Profiles for Prevention (To block files)	Select the Retentions profile you created in step 1. For the profile to appear, when defining the Retentions profile, the Custom Indicator Prevention Rules section must be set to Enabled.
Severity	Defines the severity of the alert.
Description	Add a meaningful description.

Click Next.

In the Target section, use the filters and/or select the file indicators to which to apply the rule.

Note

You can't change the Preventable = True, Status = Active and Type = File filters, which comply with the requirements of the supported indicator type for Prevention on the Agent.

Filter	Description
Value	The hash value of the field (SHA256 or MD5).
Verdict	The reputation of the indicator: Malicious, Suspicious, Benign, Unknown
Has Related Alerts	Whether the indicator has related alerts.
Campaign	Whether the indicator is part of an existing campaign.
Mitre ID	Mitre ID associated with the related alerts.
Mitre Tactic	Mitra Tactic associated with the related alerts.
Tags	The tags applied to indicators.
Confidence	The level of confidence.
Aggregated Reliability	The reliability score such as A - Completely reliable.
Feed	The source (script, manual, etc.) that last set the indicator's expiration status.

Click Next and then save the rule.

Add the indicator rule to the Restrictions Profile.
1. Go to Endpoints → Policy Management → Prevention → Profiles.
2. Edit the Restrictions Profile you created in step 1.
3. In the Custom Indicator Prevention Rules tab, select the indicator rule you created in step 2.
4. Save the Profile.

Example 1. Create a prevention rule blocking indicators from a feed

In this example, create an Indicator Prevention rule, which blocks file indicators using the Unit 42 Intel Feed and then generates an alert.

Before you begin create a Restrictions Profile called JC-Win-R-O1, with the Custom Indicator Prevention Rules section set to Enabled.

Create a Prevention Indicator Rule and in the General section, add the following parameters.
Field
Value
Rule Name
JC-IR-Prevent-02
Select Profiles For Prevention (To Block Their Files)
JC-WIN-R-01
Severity
Medium
Description
To raise prevention on IOCs from Unit 42 Intel Feed
In the Target Section, select the Feed=Unit 42 Intel filter.
In the Restrictions Profile, add the indicator rule.

Field	Value
Rule Name	JC-IR-Prevent-02
Select Profiles For Prevention (To Block Their Files)	JC-WIN-R-01
Severity	Medium
Description	To raise prevention on IOCs from Unit 42 Intel Feed

When a File indicator from Unilt 42 Intel is found, the XDR Agent blocks the indicator.

An alert is generated in Cortex XSIAM. The Alert Source is XDR Agent, severity is medium and the Action is Prevented (Blocked).

Note

The Indicator Rule shows the number of alerts generated by the rule, You can view the alerts that were generated using the Indicator rule, by right-clicking the rule and select View related alerts.

Create a Detection rule

After you create a detection rule, Cortex XSIAM searches indicators in your tenant and raises an alert if a match is detected. Detection rules apply for File, Domain, and IP Address indicator types.

Select Detection & Threat Intel → Threat Intel Management → Indicator Rules → Add Rule → Detection Rule.
From the Create New Prevention Rule wizard, in the General section, add the following parameters:
Parameters
Parameter
Description
Rule Name
Add a meaningful name.
Severity
Defines the severity of the alert.
Description
Add a meaningful description.
Click Next.

In the Target section, use the filters and/or select the file indicators to which to apply the rule.

Note

You can't change the Detectable = True and Status = Active filters which comply with the requirements of the supported indicator type for detection.

Filter	Description
Value	The hash value of the field (SHA256 or MD5), IP address, or domain.
Verdict	The reputation of the indicator: Malicious, Suspicious, Benign, Unknown
Has Related Alerts	Whether the indicator has related alerts.
Campaign	Whether the indicator is part of an existing campaign.
Mitre ID	Mitre ID associated with the related alerts.
Mitre Tactic	Mitra Tactic associated with the related alerts.
Tags	The tags applied to indicators.
Confidence	The level of confidence.
Aggregated Reliability	The reliability score such as A - Completely reliable.
Feed	The source (script, manual, etc.) that last set the indicator's expiration status.
Type	The indicator type (Domain, File, IP)

Click Next and then save the rule.
If the indicator rule has generated alerts, right-click the rule and select View related alerts.

Example 2. Create a detection rule from feeds

In this example, create a detection rule from many feeds, such as Unit 42 Intel, AzureRiskyUsers, and Mail-Sender that returns a malicious verdict.

In the General section, add the following parameters.
Field
Value
Rule Name
JC-IR-Prevent-01
Severity
Medium
Description
To raise detection on all indicators uploaded from feeds with a malicious verdict.
In the Target Section, select Feed (Select All) and Verdict = Malicious.
In the Restrictions Profile, add the indicator rule.

Field	Value
Rule Name	JC-IR-Prevent-01
Severity	Medium
Description	To raise detection on all indicators uploaded from feeds with a malicious verdict.

When a malicious verdict is found from the feed, an alert is generated. The Alert Source is Threat Intelligence, severity is medium and the Action is Detected.

Note

The Alert source is Threat Intelligence.

Manage Indicator Rules

The Indicator Rules page displays the following fields for each rule:

Field	Description
Rule ID	Unique identifier for the rule.
Creation Date	Timestamp of when the rule was created.
Modification Date	Timestamp when the rule was edited.
Name	Name of the rule.
Type	Whether the rule is a Prevention or Detection type rule.
Target	Hash, IP address, File, or domain value associated with the rule.
Severity	Level of severity associated with the rule.
# of alerts	Number of alerts generated by the rule.
Created by	Email address of the user who created the rule.
Description	Optional description associated with the rule.
Status	Whether the rule is Enabled or Disabled.
Used in profiles	Cortex XDR agent Restriction Profile associated with the rule.

Note

if an indicator matches multiple indicator rules, the highest severity rule is used. If all have the same severity, the rules are used by first created.

In the Indicator Rules table, right-click a rule to perform actions, including the following:

Action	Description
View related alerts	View alerts generated by the rule.
Disable/Enable	Depending on the current status, Disable or Enable the rule.
Edit Rule	Modify the rule.
Save as new	Create a new rule using the current rule configurations.
Delete	Delete the rule.

Generate alerts from indicators using indicator rules for prevention and detection - Threat Intel Management Guide - Cortex XSIAM - Cortex - Security Operations

Threat intel management

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Create a Prevention Rule

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Create a Detection rule

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Manage Indicator Rules

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