Alert suppression rules can help mute, acknowledge, or shrink the visibility of alerts based on suppression logic defined by security analysts. This allows administrators to concentrate on critical alerts that require immediate intervention.
Alert suppression uses three mechanisms:
- Suppress according to Alert: This type of rule will silence alerts that have similar properties, regardless of the entities they are originating from.
- Suppress according to Source: With this rule, alerts are suppressed based on the similarity of their sources.
- Suppress according to Entity: This suppresses alerts from similar entities.
In practice, alert suppression rules are created and managed via the Microsoft Defender Security Center console under Advanced hunting and Automated investigation and response (AIR).
Creating Alert Suppression Rules
Let’s see an example of creating an alert suppression rule in the Microsoft Defender Security Center.
- Navigate to the “Automated investigation and response” settings.
- Click on “Manage alert suppression rules.”
- Select “New rule.”
- Fill in the rule details: Rule name, Rule criteria (You can select a suggested rule or specify your rule), and Rule Action (Suppress alert, Dedupe alert, or Plumb alert aggregation)
- Submit the rule.
Managing Alert Suppression Rules
Maintaining suppression rules is equally as important as their creation, ensuring that they remain current and effective. Here’s how you can manage these rules from the Microsoft Defender Security Center.
- Navigate to the “Automated investigation and response (AIR)” settings.
- From here, click on “Manage alert suppression rules.”
- You will see your current list of rules. From here, you can add or delete rules, view details, modify, enable/disable, and see the rule’s statistics.
These functionalities allow you to manage these rules effectively, which ties back to the core skills required for the SC-200 exam.
Conclusion
Efficient creation and management of alert suppression rules are fundamental skills for a Security Operations Analyst to master as they support effective triaging and prioritization of security alerts. These skills are also vital for the Microsoft SC-200 exam, and an understanding of the concepts highlighted in this article can enhance your preparation for the certification. Practice creating and managing these rules on Microsoft Defender Security Center, and you will be prepared to handle them in real-world situations and nail that aspect of the exam.
Practice Test
True or False: Alert suppression rules can be used to reduce noise in the alert queue.
- True
- False
Answer: True
Explanation: Alert suppression rules assist in reducing the voluminous noise in the alert queue by suppressing similar repetitive alerts within a specific time frame.
What is the function of alert suppression rules in Microsoft Security Operations?
- a) Increments the volume for sound alerts
- b) Sends an email notification for each alert
- c) Suppresses repetitive, similar alerts within a specific time frame
- d) Always filters out all security alerts
Answer: c) Suppresses repetitive, similar alerts within a specific time frame
Explanation: Alert suppression rules are designed to reduce noise and improve efficiency by suppressing the generation of similar alerts within a specified time period.
True or False: An indiscriminate use of alert suppression can lead to overlooking legitimate threats.
- True
- False
Answer: True
Explanation: While alert suppression is a useful tool for managing the number of alerts generated, using it indiscriminately can lead to important or legitimate threats being overlooked.
What is the minimum and maximum duration for suppressing alerts in Azure Sentinel?
- a) 1 minute and 1 day respectively
- b) 1 hour and 1 week respectively
- c) 15 minutes and 24 hours respectively
- d) 1 second and 1 month respectively
Answer: c) 15 minutes and 24 hours respectively
Explanation: In Azure Sentinel, the minimum threshold for suppressing an alert is 15 minutes and the maximum is 24 hours.
True or False: You can customize alert suppression rules to suit the security needs of your organization.
- True
- False
Answer: True
Explanation: Alert suppression rules can be tailored to suit the unique security needs and priorities of your organization, thereby ensuring relevant alerts are not overlooked.
What is NOT a valid Suppression method in alert suppression rules?
- a) Suppressing based on alert properties
- b) Suppressing based on entities
- c) Suppressing based on IP address range
- d) Suppressing based on alert source
Answer: c) Suppressing based on IP address range
Explanation: Suppression methods in Azure Sentinel include alert properties, entities, and alert source, but not IP address range.
True or False: An increase in alert suppression can lead to a decrease in system security.
- True
- False
Answer: True
Explanation: If too many alerts are suppressed, there is a risk of missing out on legitimate security threats, leading to a decrease in overall system security.
Alert suppression rules can be created on which of the following platforms?
- a) Azure Defender
- b) Microsoft 365 Defender
- c) Sentinel
- d) All the Above
Answer: d) All the Above
Explanation: Alert suppression rules can be created in Azure Defender, Microsoft 365 Defender and Azure Sentinel to manage and reduce alert noise.
True or False: Alert suppression rules are temporary and cannot be saved for future use.
- True
- False
Answer: False
Explanation: Alert suppression rules once created can be saved and reused as per the requirement. They are not temporary and can be applied as long as needed.
Which of the following is not true about managing alert suppression rules?
- a) You can enable or disable alert suppression rules at any time.
- b) Once created, alert suppression rules cannot be edited.
- c) Alert suppression rules can be deleted if not needed.
- d) The duration for which alerts are suppressed can be specified.
Answer: b) Once created, alert suppression rules cannot be edited.
Explanation: Alert suppression rules can be edited after their creation, giving users the flexibility to adapt them as per changing requirements.
Interview Questions
What is alert suppression in Microsoft Security Operations Center?
Alert suppression in Microsoft Security Operations Center refers to the process of reducing the number of unnecessary or false positive alerts to focus on high priority alerts that require immediate action.
What is the purpose of creating alert suppression rules in Microsoft Security Operations Center?
The purpose of creating alert suppression rules is to help in decreasing the number of non-actionable alerts, thus allowing the security operations analysts to focus more on severe and actionable alerts.
How can you create an alert suppression rule in Microsoft Security Operations Center?
To create an alert suppression rule in Microsoft Security Operations Center, navigate to the Alerts page in the security center, select the alerts you want to apply suppression to, and then create a new suppression rule based on the specific conditions you define.
Can you modify an existing alert suppression rule in the Microsoft Security Operations Center?
Yes, an existing alert suppression rule can be modified in the Microsoft Security Operations Center. The user can update the rule conditions, the suppression window, or the entities to exclude or include.
What happens when an alert matches a suppression rule in the Microsoft Security Operations Center?
When an alert matches a suppression rule, the system reduces the frequency of that alert. The suppressed alert will still be recorded in the system, but it will not generate notifications.
Can you delete a suppression rule in Microsoft Security Operations Center?
Yes, a suppression rule can be deleted in the Microsoft Security Operations Center. Once a suppression rule is deleted, it will no longer suppress the associated alerts.
Can multiple suppression rules be applied to a single alert in Microsoft Security Operations Center?
Yes, multiple suppression rules can be applied to a single alert if the alert matches the conditions specified in those rules.
What aspects should be considered in defining the conditions for an alert suppression rule?
Aspects to consider include the severity of the alert, alert frequency, entities related to the alert, and false positive rates.
Is it possible to test the effectiveness of a suppression rule in Microsoft Security Operations Center?
Yes, Microsoft Security Operations Center provides a preview feature that allows users to see the number of alerts that would have been suppressed if the rule was applied in the past.
Does Microsoft Security Operations Center provide a default alert suppression rule?
No, Microsoft Security Operations Center doesn’t provide a default alert suppression rule. Users have to create their own rules based on their specific needs.
Can user set a duration for alert suppression rules in Microsoft Security Operations Center?
Yes, while setting up an alert suppression rule, you can specify a suppression window, which is the duration for which the rule should apply.
What is the purpose of the suppression reason in the alert suppression rule?
The suppression reason in the alert suppression rule helps in documenting why a specific rule was created. This provides clarity and context for future analysis and reviews.
Is it possible to reactivate a suppressed alert in Microsoft Security Operations Center?
No, once an alert is suppressed, it cannot be reactivated. However, the suppressed alert will exist for review and analysis.
Can you use the API to create and manage alert suppression rules in Microsoft Security Operations Center?
Yes, Microsoft Security Operations Center provides API endpoints to create, read, update, and delete alert suppression rules.
Is there a limit to the number of alert suppression rules you can create in Microsoft Security Operations Center?
Microsoft has not specified a limit for the number of alert suppression rules that can be created. However, for optimal performance, it is recommended to keep the number of rules manageable and relevant.
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