SCS-C02 Threat Detection and Incident Response — Timed 40 Questions

Question 1

A security team suspects that an attacker has compromised an EC2 instance and is using it to launch outbound DDoS attacks. The team needs to quickly isolate the instance while preserving forensic data. Which combination of actions should the team take? (Choose TWO.)

40 minute time limit — choose an answer to begin.

Accepted Answer

Apply a restrictive security group that blocks all outbound traffic.. Applying a restrictive security group that blocks all outbound traffic immediately stops the EC2 instance from sending any network packets, including DDoS traffic, without terminating the instance. This preserves the running state and allows forensic data collection from the instance's memory and disk. Security groups act as a stateful virtual firewall at the instance level, so blocking outbound traffic effectively isolates the instance from the network.

Answer

Modify the network ACL for the subnet to deny all outbound traffic.

Answer

Detach the instance from the Auto Scaling group.

Answer

Terminate the EC2 instance immediately.

Question 2

During an incident response, a security engineer needs to collect memory and disk forensics from a running EC2 Windows instance without causing the instance to crash. The engineer has AWS Systems Manager SSM Agent installed. Which method should the engineer use?

Accepted Answer

Create an EBS snapshot of the root volume.. An EBS snapshot provides a forensic copy of the root volume but cannot capture volatile memory (RAM). To collect memory forensics, the engineer must run a memory dump tool via SSM Run Command before taking the snapshot. Since none of the options include a memory capture method, the question should be revised to either ask specifically for disk forensics or add an option for memory capture. As written, the question is invalid.

Answer

Create an AMI of the instance.

Answer

Use AWS Systems Manager Inventory to collect memory and disk information.

Answer

Use AWS Backup to create a backup of the instance.

Question 3

A company uses AWS Organizations with multiple accounts. The security team wants to ensure that all API calls in the organization are logged and retained for at least one year. Which AWS services or features should be used to meet these requirements? (Choose TWO.)

Accepted Answer

Amazon S3 lifecycle policy to transition logs to S3 Glacier after one year.. An Amazon S3 lifecycle policy can automatically transition CloudTrail log objects from S3 Standard to S3 Glacier after one year, meeting the retention requirement cost-effectively. Option E is correct because AWS CloudTrail with an organization trail logs all API calls across all accounts in the AWS Organization, ensuring comprehensive logging.

Answer

Amazon GuardDuty with threat detection enabled.

Answer

AWS Config with recording enabled for all resources.

Answer

VPC Flow Logs for all VPCs.

Question 4

A security engineer reviews the CloudTrail log entry in the exhibit. The engineer notices that an EC2 instance was launched using an AdminRole. Which additional information would help determine if this is a legitimate action or a potential compromise?

Accepted Answer

The source IP address 203.0.113.50 is from an unexpected geographic location not associated with the company.. The source IP address 203.0.113.50 is from an unexpected geographic location not associated with the company. In CloudTrail, the `sourceIPAddress` field records the originating IP of the API call. If an AdminRole is used from an IP outside the company's known CIDR ranges or geographic regions, it strongly indicates a potential compromise—such as stolen credentials or an attacker using the role from an unauthorized network. This is a key indicator of anomalous behavior in threat detection.

Answer

The AMI ID ami-0abcdef1234567890 is not a standard Amazon-provided AMI.

Answer

The instance type m5.xlarge is unusually large compared to previous launches.

Answer

The security group sg-0123456789abcdef0 allows inbound SSH from 0.0.0.0/0.

Question 5

During a security incident, a security engineer needs to verify whether an EC2 instance's security group allowed inbound SSH from a specific IP address at the time of the incident. Which AWS service or feature should the engineer use to obtain this historical information?

Accepted Answer

AWS Config configuration history.. AWS Config configuration history records changes to security group rules, including the addition or removal of inbound SSH allow rules. By querying the configuration history for the specific security group, the engineer can determine the exact state of the rules at the time of the incident, including whether a specific IP address was allowed. This is the only service that provides a historical record of security group rule configurations.

Answer

Amazon CloudTrail event history.

Answer

AWS Systems Manager Inventory.

Answer

VPC Flow Logs.

Question 6

A security engineer is implementing automated incident response. The engineer wants to use AWS Lambda to automatically remediate GuardDuty findings. What is the recommended pattern to trigger the Lambda function?

Accepted Answer

Configure an Amazon EventBridge rule to match GuardDuty findings and invoke the Lambda function.. Amazon EventBridge is the recommended pattern because it natively integrates with AWS GuardDuty to receive all finding events in near real-time. By configuring an EventBridge rule that matches GuardDuty finding types (e.g., 'UnauthorizedAccess:EC2/SSHBruteForce'), you can directly invoke a Lambda function for automated remediation without polling or intermediate services. This pattern is serverless, event-driven, and follows AWS best practices for decoupled incident response.

Answer

Subscribe the Lambda function to an SNS topic that GuardDuty publishes findings to.

Answer

Use CloudWatch Logs subscription filter to trigger Lambda on GuardDuty log entries.

Answer

Have the Lambda function poll the EC2 instance metadata for threat indicators.

Question 7

A company uses AWS Systems Manager Patch Manager to patch EC2 instances. During a security incident, the security team needs to quickly patch a critical vulnerability across all Windows instances in a specific AWS region. Which steps should the team take? (Choose TWO.)

Accepted Answer

Assign the patch baseline to the instances by specifying a patch group.. Assigning a custom patch baseline to instances via a patch group allows the security team to target specific Windows instances for patching. Patch Manager uses patch groups to associate instances with a specific patch baseline, ensuring only the desired instances receive the critical patch. This approach provides granular control over which instances are patched during an incident.

Answer

Tag all instances with 'PatchGroup=Critical' to include them in the patching.

Answer

Use the AWS-provided default patch baseline for Windows.

Answer

Use SSM Run Command to execute a script that downloads and installs the patch.

Question 8

A company runs a critical web application on a fleet of EC2 instances behind an Application Load Balancer (ALB). The application uses an Aurora MySQL database. The security team receives an alert from Amazon GuardDuty that a specific EC2 instance is exhibiting behavior consistent with a cryptocurrency mining attack, including outbound connections to known mining pools. The instance is part of an Auto Scaling group that uses a launch template with a security group that allows outbound HTTPS traffic to 0.0.0.0/0. The security engineer needs to contain the incident while minimizing downtime for the application. The engineer has already taken a forensic snapshot of the instance's EBS volume. Which course of action should the engineer take next?

Accepted Answer

Detach the instance from the Auto Scaling group and isolate it by removing all security group rules.. The correct course of action is to isolate the compromised instance without disrupting the rest of the fleet. Detaching the instance from the Auto Scaling group removes it from management and triggers a replacement to maintain capacity. Removing or replacing its security group rules (or attaching a quarantine security group) halts all traffic, including outbound communication to mining pools. This contains the threat while minimizing downtime. Option A is wrong because the security group is defined in the launch template and is shared across all instances; modifying it would block outbound traffic for the entire application, causing a full outage. Option D is less ideal because immediate termination loses the ability to conduct further live forensics (though a snapshot exists) and may be hasty without first isolating the instance.

Answer

Modify the security group attached to the instance to deny all outbound traffic, and let Auto Scaling launch a replacement instance.

Answer

SSH into the instance and run a script to kill the mining process.

Answer

Immediately terminate the compromised EC2 instance and allow Auto Scaling to launch a new instance.

Question 9

A security engineer is investigating a potential credential compromise. An IAM user's access key was used to launch EC2 instances in a region where the user has never operated before. The engineer wants to quickly identify all API calls made by this user in the last 24 hours, including the source IP addresses. Which AWS service or feature should be used?

Accepted Answer

AWS CloudTrail. AWS CloudTrail is the correct service because it records all API calls made by IAM users, including the source IP address, user identity, and request details. By querying CloudTrail logs for the specific IAM user's access key over the last 24 hours, the engineer can identify every EC2-related and other API call, along with the originating IP addresses, enabling rapid investigation of the potential credential compromise.

Answer

VPC Flow Logs

Answer

AWS Trusted Advisor

Answer

Amazon CloudWatch Logs

Question 10

A company uses AWS Organizations with multiple accounts and has enabled AWS Security Hub in the management account. The security team wants to automatically remediate a specific finding type that appears in Security Hub. Which combination of services should be used to achieve this?

Accepted Answer

Amazon EventBridge and AWS Lambda. Amazon EventBridge can capture Security Hub findings as events using an event rule that matches the specific finding type. When the rule triggers, it invokes an AWS Lambda function that contains the remediation logic, such as modifying security group rules or disabling access keys. This combination provides a serverless, event-driven architecture for automated response to Security Hub findings.

Answer

AWS Config conformance packs and AWS Systems Manager Automation

Answer

Amazon Inspector and AWS Step Functions

Answer

Amazon GuardDuty and AWS Lambda

Question 11

A security engineer is configuring an automated incident response workflow for Amazon GuardDuty findings. Which TWO actions should the engineer take to ensure that the response is triggered for all current and future GuardDuty findings?

Accepted Answer

Create an Amazon EventBridge rule with an event pattern that matches GuardDuty finding events.. Amazon EventBridge can capture all GuardDuty findings by using an event pattern that matches the 'GuardDuty Finding' event type. This ensures that both current and future findings automatically trigger the rule without requiring manual updates or additional configuration.

Answer

Enable GuardDuty to export findings to CloudWatch Logs and then create a metric filter.

Answer

Create an Amazon SNS topic and subscribe the Lambda function to it, then configure GuardDuty to publish to SNS.

Answer

Set up a CloudWatch Logs subscription filter to forward GuardDuty logs to the Lambda function.

Question 12

Drag and drop the steps to configure AWS WAF with rate-based rules in the correct order.

Accepted Answer

Create a web ACL, then add a rate-based rule to it, then associate the web ACL with an AWS resource, then test the rate-based rule, then monitor metrics and adjust thresholds.. Rate-based rules require creating a web ACL first, then adding the rule, associating with a resource, testing, and monitoring.

Answer

Add a rate-based rule to a web ACL first, then create the web ACL, then associate with a resource, then test, then monitor.

Answer

Create a web ACL, then associate it with a resource, then add a rate-based rule, then test, then monitor.

Answer

Create a web ACL, then add a rate-based rule, then test the rule, then associate the ACL with a resource, then monitor.

Question 13

Match each AWS service to its primary security function.

Accepted Answer

AWS WAF: Web application firewall that protects against common web exploits.. These are core AWS security services with distinct purposes.

Answer

AWS WAF: Managed DDoS protection service.

Answer

AWS Shield: Threat detection service.

Question 14

Match each AWS IAM policy type to its description.

Accepted Answer

Identity-based policy: Attached to an IAM user, group, or role to define permissions. The correct matches are: Identity-based policies are attached to users, groups, or roles; Resource-based policies are attached to resources; Permissions boundaries limit maximum permissions; Session policies are passed during role assumption. Common confusions include swapping identity-based and resource-based definitions.

Answer

Identity-based policy: Attached to a resource and defines which principals can access it

Answer

Resource-based policy: Attached to an IAM user, group, or role

Question 15

A company has an AWS Lambda function that processes sensitive data. The security team wants to ensure that any errors or suspicious behavior are immediately investigated. Which combination of services should be used to send real-time notifications for anomalous function executions?

Accepted Answer

CloudWatch Logs and SNS. CloudWatch Logs can capture Lambda function execution logs, and a CloudWatch Logs metric filter can be configured to detect patterns indicative of errors or suspicious behavior (e.g., 'ERROR', 'Exception', or custom anomaly patterns). When the metric filter triggers a CloudWatch alarm, it can publish a message directly to an Amazon SNS topic, which then sends real-time notifications (e.g., email, SMS, or HTTP endpoint) to the security team for immediate investigation.

Answer

CloudTrail and SNS

Answer

AWS Config and SQS

Answer

Amazon Detective and SES

Question 16

During a security incident, a security engineer needs to preserve forensic evidence from an EC2 instance that may be compromised. The instance is running a critical application. Which approach minimizes data loss while ensuring the integrity of the evidence?

Accepted Answer

Create an EBS snapshot, then isolate the instance by modifying the security group and removing it from the load balancer.. Creating an EBS snapshot preserves the disk state at the point of the incident, capturing forensic evidence without altering the running instance. Isolating the instance by modifying the security group (e.g., removing all inbound/outbound rules) and removing it from the load balancer stops network traffic and prevents further compromise, minimizing data loss while maintaining the integrity of the evidence for later analysis.

Answer

Immediately terminate the instance to stop any ongoing malicious activity.

Answer

SSH into the instance and run forensic tools to capture memory.

Answer

Detach the instance from the Auto Scaling group and leave it running without changes.

Question 17

A company's security team wants to detect unauthorized S3 bucket access attempts in real time. Which service should they use to generate alerts when an IAM user attempts to access a bucket without proper permissions?

Accepted Answer

AWS CloudTrail with CloudWatch alarms. AWS CloudTrail logs all API calls made to S3, including access denied errors. By creating a CloudWatch alarm on the `S3 AccessDenied` event in CloudTrail logs, the security team can receive real-time alerts when an IAM user attempts to access a bucket without proper permissions. This approach directly captures the unauthorized attempt at the API level, enabling immediate detection.

Answer

Amazon GuardDuty

Answer

S3 server access logs

Answer

AWS Config

Question 18

An organization uses AWS Organizations with multiple accounts. The security team needs a centralized location to collect and analyze security findings from GuardDuty, Inspector, and Macie. Which AWS service should they use?

Accepted Answer

AWS Security Hub. AWS Security Hub is the correct service because it provides a centralized view of security alerts and compliance status across multiple AWS accounts. It aggregates findings from GuardDuty, Inspector, and Macie, normalizing them into the AWS Security Finding Format (ASFF), enabling the security team to analyze and prioritize threats in a single dashboard.

Answer

Amazon Detective

Answer

Amazon CloudWatch

Answer

AWS Config

Question 19

A security engineer is investigating a potential compromise of an EC2 instance. The instance was launched from a custom AMI. The engineer needs to determine if the AMI itself contains malicious software. Which approach provides the most thorough analysis without risking the production environment?

Accepted Answer

Launch a test instance from the AMI in an isolated VPC and run Amazon Inspector.. Launching a test instance from the AMI in an isolated VPC allows you to run Amazon Inspector, which performs automated vulnerability assessments and network reachability checks against the instance. This approach provides a thorough analysis of the AMI's software and configuration without exposing the production environment to any potential malicious activity. Amazon Inspector uses a knowledge base of common vulnerabilities and exposures (CVEs) and CIS benchmarks to identify security issues, making it effective for detecting malicious software embedded in the AMI.

Answer

Use AWS Systems Manager to run a compliance scan on the running instance.

Answer

Create an EBS snapshot from the AMI and scan the snapshot with Amazon Detective.

Answer

Launch a test instance from the AMI in an isolated VPC and analyze its behavior.

Question 20

A company wants to ensure that any deleted CloudTrail logs are detected and alerted within minutes. Which approach should they use?

Accepted Answer

Configure CloudTrail to send logs to CloudWatch Logs, create a metric filter for DeleteTrail events, and set a CloudWatch alarm to send an SNS notification.. CloudTrail management events (including DeleteTrail) are delivered to CloudWatch Logs, where a metric filter can match the exact event name. A CloudWatch alarm on that metric triggers an SNS notification within minutes, meeting the detection and alerting requirement. This approach directly monitors the CloudTrail API call that deletes the trail itself, not just the log files.

Answer

Enable S3 event notifications on the CloudTrail bucket for DELETE events.

Answer

Use AWS Config to track CloudTrail configuration changes and trigger a Lambda function.

Answer

Enable Amazon GuardDuty to monitor CloudTrail management events.