SCS-C03 AWS Certified Security – Specialty Questions and Answers

KMS grantsare purpose-built for givingtemporary, scoped permissionsto use a customer managed key without continually editing key policies. A grant can allow only the specific cryptographic operations the application process needs (for example, Encrypt/Decrypt/GenerateDataKey) and can be constrained to a particular AWS principal and (optionally) conditions. When access is no longer required, the security team canrevokethe grant immediately, returning the key to its previous access posture. This meets the “temporary access occasionally” requirement with minimal operational work and lower risk than policy churn.

Option B requires repeated key policy edits and rollbacks, which is operationally noisy and increases the chance of misconfiguration or leaving access in place longer than intended. Option A is not supported in the way described—KMS key material for standard KMS customer managed keys is not something you “export” for sharing, and exposing key material breaks managed key controls. Option D introduces significant overhead and complexity by generating/importing key material repeatedly and is not the intended model for occasional access. Grants are the standard AWS pattern for delegating KMS key usage temporarily and safely.

AWS CloudTrail data event logging is the correct solution because it is specifically designed to capture detailed, structured, and near–real-time API activity for Amazon S3 object-level operations. When S3 data events are enabled, CloudTrail records actions such as GetObject, PutObject, and DeleteObject, along with critical context including the IAM principal, source IP address, event time, request parameters, and response elements. These logs are delivered in JSON format, making them highly structured and suitable for security analysis, SIEM integration, and automated detection workflows.

Amazon S3 server access logging (option A) provides basic request-level information but does not include full IAM identity context and is delivered with a significant delay, which does not meet the near–real-time requirement. AWS Config (option C) focuses on resource configuration changes and compliance evaluation; it does not log object-level access events. Amazon Macie (option D) is a data security service that uses machine learning to discover and classify sensitive data in S3 and generate findings for anomalous access patterns, but it is not a comprehensive access logging solution.

AWS Security Specialty documentation clearly states that CloudTrail data events are the authoritative mechanism for auditing S3 object-level access with identity attribution and precise timestamps, making option B the correct and best-practice answer

Amazon GuardDuty Exfiltration:S3/AnomalousBehavior findings indicate that S3 data access patterns are consistent with data exfiltration. In this scenario, the attacker is usingtemporary credentials obtained from an EC2 instance profile, which are issued by AWS Security Token Service (STS).

According to AWS Certified Security – Specialty documentation, thefastest and most targeted remediationis to revoke the temporary session credentials associated with the compromised instance profile. This can be accomplished by removing or modifying the IAM role permissions, detaching the instance profile, or stopping the instance, which immediately invalidates the temporary credentials and prevents further S3 access.

Option B may limit outbound traffic but does not invalidate already issued credentials. Option C is a detection and classification service and does not prevent active exfiltration. Option D would block all access to the bucket, including legitimate access, and is considered overly disruptive for incident containment.

AWS incident response best practices emphasizecredential revocation as the first containment stepwhen compromise of temporary credentials is confirmed.

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty User Guide – S3 Protection

AWS STS and IAM Role Security Documentation

AWS Incident Response Best Practices

AWS Health providesreal-time visibility into events that affect AWS accounts, including abuse notifications such asAWS_ABUSE_DOS_REPORT. According to the AWS Certified Security – Specialty Study Guide, AWS Health events are natively integrated withAmazon EventBridge, enabling automated, near-real-time responses without polling or custom code.

By creating an EventBridge rule that listens for AWS Health events related to abuse reports and configuring the rule to publish messages to an SNS topic, the security engineer ensures immediate notification to the security team whenever AWS issues a DoS-related abuse report for the account.

Option A and C rely on periodic polling using Lambda functions, which introduces latency and operational complexity. Option D is incorrect because CloudTrail does not log AWS abuse notifications.

AWS documentation explicitly identifiesAWS Health + EventBridge + SNSas the recommended architecture for near-real-time operational and security alerts originating from AWS.

AWS Certified Security – Specialty Official Study Guide

AWS Health User Guide

Amazon EventBridge Documentation

AWS Incident Response Best Practices

Option D is the correct solution because it provides fully automated, real-time detection and mitigation of application-layer (Layer 7) DDoS attacks with no manual intervention. AWS Shield Advanced includes automatic application layer DDoS mitigation when it is enabled for supported resources such as Amazon CloudFront distributions. This feature continuously monitors traffic patterns and, when an attack is detected, automatically deploys AWS WAF rules to mitigate malicious requests.

Adding a rate-based rule to the AWS WAF web ACL further strengthens protection by automatically blocking IP addresses that exceed a defined request threshold, which is a common characteristic of Layer 7 DDoS attacks. This combination aligns directly with AWS best practices for protecting web applications against volumetric and application-layer threats.

Option A only provides alerting and visibility but does not ensure automated mitigation. Option B includes proactive engagement with the AWS DDoS Response Team, which is valuable for complex or large-scale attacks but still involves human interaction and therefore does not meet the “no manual effort” requirement. Option C introduces unnecessary complexity and is not recommended for protecting CloudFront-based applications against Layer 7 DDoS attacks.

AWS Security Specialty documentation explicitly recommends AWS Shield Advanced with automatic application layer DDoS mitigation and AWS WAF rate-based rules for fully automated, real-time protection of public web applications.

AWS incident response best practices emphasize immediate containment, preservation of evidence, and safe forensic investigation. According to the AWS Certified Security – Specialty Study Guide, when an EC2 instance is suspected of compromise, security teams should avoid logging in to the instance or installing additional tools, as these actions can alter evidence and increase risk.

Terminating the compromised instance after ensuring that its Amazon EBS volumes are preserved prevents further malicious activity immediately. By setting the EBS volumes to not delete on termination, all disk data is retained for forensic analysis. Launching a new, clean EC2 instance in a different subnet or Availability Zone with preinstalled diagnostic tools allows investigators to safely attach and analyze the compromised volumes without executing potentially malicious code.

Option A introduces significant risk by logging in to the compromised instance and modifying security controls during active compromise. Option B delays containment and allows continued outbound traffic during investigation steps. Option D is invalid because AWS WAF cannot be attached directly to Amazon EC2 instances and does not control outbound traffic.

AWS documentation strongly recommends isolating or terminating compromised resources and performing offline analysis using detached storage volumes. This approach ensures immediate mitigation, preserves forensic integrity, and aligns with AWS incident response frameworks.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS Incident Response Best Practices

Amazon EC2 and EBS Forensics Guidance

AWS Well-Architected Framework – Security Pillar

Amazon S3 Block Public Access provides centralized controls to prevent public access through bucket policies and ACLs. AWS Certified Security – Specialty guidance recommends enabling Block Public Access to reduce accidental exposure and to enforce guardrails that override public grants. Enabling Block Public Access on the bucket removes current public exposure when combined with correcting policies/ACLs and prevents future misconfiguration. To ensure the bucket cannot be made public again, the security engineer must prevent principals from disabling Block Public Access. An SCP that denies s3:PutPublicAccessBlock prevents changes that would remove or weaken the PublicAccessBlock configuration, enforcing the guardrail across the OU or account. Options A and D do not directly address public exposure control. Option B denies object reads but does not ensure public access cannot be re-enabled; it also does not address the root misconfiguration pathways and could disrupt legitimate access patterns. Option C specifically combines the correct preventive control (PublicAccessBlock) with organizational enforcement to stop future reversal.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon S3 Block Public Access

AWS Organizations SCP Guardrails for S3 Controls

VPC Flow Logs require an IAM role that CloudWatch Logs can use to publish flow log records. AWS documentation and AWS Certified Security – Specialty materials explain that the VPC Flow Logs service must be able to assume the IAM role through its trust policy. The trust relationship must include the service principal vpc-flow-logs.amazonaws.com. If the trust policy does not allow this principal to assume the role, flow logs cannot be delivered and no records will appear in the CloudWatch Logs log group even when traffic exists. logs:GetLogEvents is not required for delivery; it is used for reading logs. The security engineer’s ability to assume the role is not relevant because the service, not the engineer, assumes it. Tagging permissions are not required for basic log delivery. Therefore, the most likely cause is an incorrect trust policy that prevents the VPC Flow Logs service principal from assuming the role.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon VPC Flow Logs IAM Role Requirements

IAM Trust Policies for AWS Services

SSE-S3 uses AWS-managed keys and does not provide customer control. AWS Certified Security – Specialty documentation states that SSE-KMS with customer managed keys allows full control, auditing, and key rotation. The security engineer must first create a customer managed KMS key, then update the bucket to use SSE-KMS. Existing objects must be re-encrypted to ensure compliance.

SSE-C requires the application to manage keys, increasing complexity and risk. AWS managed keys do not meet the requirement for customer-controlled encryption.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon S3 Encryption Options

AWS KMS Customer Managed Keys

Amazon GuardDuty is afully managed, organization-aware threat detection servicethat continuously analyzes AWS logs such as CloudTrail events, VPC Flow Logs, DNS logs, EKS audit logs, and RDS activity. According to the AWS Certified Security – Specialty Official Study Guide, GuardDuty is designed to operate atscale across AWS Organizations with minimal operational overhead.

By designating a GuardDuty administrator account in the organization’s management account and enabling GuardDuty organization-wide, the company can automatically enable threat detection across hundreds of AWS accounts. EnablingEKS Protectionallows GuardDuty to analyze Kubernetes audit logs for suspicious activity, whileRDS Protectionprovides anomaly detection for Amazon Aurora databases.

Options B, C, and D require custom log aggregation, processing, and analytics pipelines, which significantly increase operational effort and maintenance complexity. Amazon Inspector does not analyze logs, Athena-based analysis is manual, and Kinesis plus Lambda requires custom detection logic.

AWS documentation explicitly identifiesGuardDuty with AWS Organizations integrationas the recommended solution for centralized, automated threat detection across multi-account environments with minimal operational effort.

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty User Guide

GuardDuty Organization Administration Documentation

AWS IAM Identity Center relies on SAML assertions and attribute mappings to associate federated users with identities, groups, and permission sets. According to the AWS Certified Security – Specialty documentation, when changing identity providers while maintaining the same underlying directory, existing users and group identities can be preserved by updating attribute mappings to align with the new IdP’s SAML assertions.

By modifying the attribute mappings, IAM Identity Center can correctly interpret usernames, group memberships, and unique identifiers sent by the new IdP without requiring changes to AWS account roles or permission sets. This approach minimizes operational effort and avoids disruption to access management.

Option A unnecessarily disables identities and causes access outages. Option C is incorrect because IAM Identity Center abstracts role trust relationships, and roles do not directly trust the IdP. Option D is unrelated to federation source configuration and only affects authentication timing issues.

AWS best practices recommend updating attribute mappings when switching IdPs that share the same directory source.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS IAM Identity Center SAML Federation

AWS Identity Federation Best Practices

Amazon GuardDuty provides continuous threat detection for compromised instances by analyzing VPC Flow Logs, DNS logs, and CloudTrail events. According to AWS Certified Security – Specialty guidance, GuardDuty is the fastest service to enable for detecting malware and compromised EC2 instances.

To notify the security team, Amazon SNS provides a native email notification mechanism with minimal setup. Amazon EventBridge integrates directly with GuardDuty findings and can filter based on severity. Creating an EventBridge rule that matches high severity GuardDuty findings and publishes to SNS ensures immediate notification.

Security Hub is not required for this use case and adds additional setup time. Amazon SQS does not support email subscriptions.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty Findings and Severity

Amazon EventBridge Integration with GuardDuty

To ensure traffic from a VPC to AWS KMS stays on the AWS network and does not use public endpoints, you should use aninterface VPC endpoint (AWS PrivateLink) for KMS. Creating aVPC endpoint for KMS with private DNS enabled(Option C) causes standard KMS DNS names (for example, kms. < region > .amazonaws.com) to resolve to theprivateendpoint IPs inside the VPC, routing requests over the AWS private network rather than through the internet. This is the core networking control that satisfies “no public service endpoints.”

To enforce that only calls that come through the intended VPC endpoint can use the key, add an authorization guardrail in theKMS key policyusing the aws:sourceVpce condition (Option A). This ensures that even if a principal has credentials, KMS will deny usage unless the request is made via the specified VPC endpoint, preventing accidental or malicious use over public paths.

Option B is neither necessary nor sufficient: removing an internet gateway does not prevent all public endpoint use (NAT, other egress paths, or other VPCs could still be involved) and can break workloads. Option D is unrelated to runtime KMS API traffic. Option E is weaker because SourceIp checks can be bypassed via other AWS network paths and does not guarantee PrivateLink usage the way sourceVpce does.

In IAM Identity Center, users see accounts and permission sets in the AWS access portal based onassignments. Here, the new permission set was assigned to theDevOps groupfor a specific member account. Sinceall developers except onecan see the permission set, the permission set itself and the account assignment are working correctly. The most likely cause is that the remaining developer isnot actually a memberof the DevOps group in the identity source (AWS Directory Service / Active Directory), or their group membership is not reflected due to missing/incorrect directory group assignment.

The least disruptive fix is to ensure the developer’s identity is correctly included in theDevOpsgroup within the directory. Once the user is a member of the assigned group (and after normal identity sync/refresh behavior), IAM Identity Center will evaluate the user as entitled to that permission set, and it will appear in the access portal.

Option B is unnecessary because the assignment is already effective for others. Option C is unrelated; service-linked roles for Organizations do not determine portal entitlements. Option D would not explain why only one user cannot see the permission set; if console access were misconfigured, it would affect all users assigned that permission set.

WithSSE-KMS, authorization is a two-part check: the caller must have S3 permissions to read the objectandthe caller must be allowed to use the KMS key for decryption. Even if an IAM policy grants kms:Decrypt, the request will still fail if theKMS key policydoes not allow the principal (or does not allow the account to delegate use of the key). KMS key policies are authoritative: they can prevent key usage even when IAM policies appear to allow it.

A common misconfiguration is editing the key policy and removing the statement that grants the AWS account (or key administrators) the ability to manage and delegate permissions for the key—often described as removing “Enable IAM user permissions” or otherwise blocking the account from using IAM policies to authorize key usage. In that case, the IAM user’s kms:Decrypt permission in IAM is not sufficient because the key policy no longer permits it, resulting in Access Denied when S3 attempts to call KMS on the user’s behalf during GetObject.

Option A is not required for decrypting data (DescribeKey is useful for discovery but not necessary for GetObject). Option B would not inherently cause access denied if permissions align. Option C is incorrect because same-account S3 access can be granted purely via IAM without a bucket policy. Therefore, the key policy change is a valid reason.

When AWS IAM Identity Center is used to manage user access across an AWS Organization, Identity Center is the authoritative control plane for enabling and disabling user access. According to the AWS Certified Security – Specialty Official Study Guide, disabling a user in IAM Identity Center immediately prevents that user from accessing any AWS account or role that is assigned through permission sets, satisfying the requirement to stop access organization-wide.

Disabling an IAM user in a single account or removing attached policies (Options A and B) does not prevent access through IAM Identity Center–managed roles in other accounts. Option C is incomplete because removing permission sets does not immediately disable authentication and still requires querying logs from an unsupported source.

For investigation and evidence collection, AWS CloudTrail organizational event data stores provide centralized, queryable access to all management and data events across all accounts in the organization. CloudTrail Lake enables security engineers to run SQL-based queries directly against event data without exporting logs to other services. This allows rapid collection of all actions that the compromised user performed during the last 7 days.

AWS documentation explicitly identifies the combination of IAM Identity Center for access revocation and CloudTrail Lake for organization-wide investigation as a best practice for identity-related incident response.

AWS Certified Security – Specialty Official Study Guide

AWS IAM Identity Center Documentation

AWS CloudTrail Lake User Guide

AWS Incident Response Best Practices

For the earliest detection of abnormal spend, the most direct and purpose-built capability isAWS Cost Anomaly Detection. It continuously evaluates spend patterns and uses machine learning to identify unexpected cost increases soon after they begin, then sends alerts based on the configured thresholds. By creating acost monitor(for example, for linked accounts, services, or cost categories) and configuring an alert to publish toSNS, the security team can receive near-real-time notifications when costs deviate beyond an expected baseline. This is well suited for detecting compromise-driven spend (such as abused EC2 instances serving phishing pages, crypto-mining, or data exfiltration patterns that raise transfer costs).

Option A introduces significant operational overhead and delays because billing/usage exports are not guaranteed to be updated on an hourly cadence in a way that consistently outperforms the native anomaly detector, and the company would be maintaining custom analytics logic. Option C is explicitly slower (daily manual review). Option D may detect suspicious traffic but is indirect for “earliest cost increase” detection and depends on building/operating a separate analytics pipeline; also, not all cost anomalies are visible from flow logs. Therefore, Cost Anomaly Detection provides the fastest and lowest-overhead alerting for unexpected spend.

AWS KMS provides condition keys that can be used to tightly scope how and where a customer managed key can be used. According to the AWS Certified Security – Specialty Study Guide, the kms:ViaService condition key is specifically designed to restrict key usage to requests that originate from a particular AWS service in a specific Region.

By configuring the key policy to allow KMS cryptographic operations only when kms:ViaService equals s3. < region > .amazonaws.com, the security engineer ensures that the key can be used exclusively by Amazon S3. Even if other IAM principals have permissions to use the key, the key cannot be used by other services such as Amazon EC2, Amazon RDS, or AWS Lambda.

Option A is incorrect because AWS services do not assume identities in key policies. Options C and D modify IAM role policies, which do not control how a KMS key is used by AWS services. AWS documentation clearly states that service-level restrictions must be enforced at the KMS key policy level using condition keys.

This approach enforces strong separation of duties and limits blast radius, which aligns with AWS security best practices.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS KMS Key Policy Condition Keys

AWS KMS Best Practices

AWS CloudTrail Lake is purpose-built to store, query, and analyze CloudTrail events, including data events, without requiring additional infrastructure. The AWS Certified Security – Specialty documentation explains that CloudTrail Lake provides immutable event storage with configurable retention periods, including multi-year retention, which satisfies long-term compliance requirements such as 7-year retention. Events are stored in an append-only, immutable format managed by AWS, reducing operational complexity.

CloudTrail Lake supports SQL-based queries for complex analysis directly against the event data, eliminating the need to export logs to other services for querying. Additionally, CloudTrail Lake includes built-in dashboards and integrations that enable visualization of event trends and patterns without standing up separate analytics or visualization platforms.

Option B is invalid because CloudTrail Event History only retains events for up to 90 days and does not support long-term retention or advanced querying. Option C introduces high operational overhead and cost by requiring persistent Amazon EMR clusters and additional services. Option D incurs ongoing ingestion, indexing, and storage costs for OpenSearch Service over a 7-year period, making it less cost-effective than CloudTrail Lake.

AWS documentation positions CloudTrail Lake as the most cost-effective and operationally efficient solution for long-term, queryable CloudTrail event storage and visualization.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS CloudTrail Lake Architecture and Retention

AWS CloudTrail Data Events Overview

Amazon GuardDuty provides continuous monitoring for anomalous and malicious network activity by analyzing VPC Flow Logs, DNS logs, and CloudTrail events. Enabling GuardDuty across accounts requires minimal configuration and immediately satisfies the requirement to monitor endpoints for anomalous network traffic, as described in the AWS Certified Security – Specialty Study Guide.

Encrypting data in transit for applications behind Elastic Load Balancing is most efficiently achieved by using AWS Certificate Manager (ACM). ACM provisions and manages TLS certificates automatically, and integrating ACM with ELB enables encrypted communication without manual certificate management.

For encryption at rest in Amazon S3, AWS best practices recommend enforcing server-side encryption using AWS KMS. An S3 bucket policy that denies PutObject requests unless the x-amz-server-side-encryption condition is present ensures that all uploaded objects are encrypted at rest using KMS-managed keys. This provides strong encryption guarantees with minimal operational effort.

Option A is unnecessary because Amazon Inspector focuses on vulnerability assessment, not encryption or network anomaly detection. Option C adds network complexity and is not required to meet the stated requirements. Option E is incorrect because x-amz-meta-side-encryption is not a valid enforcement mechanism.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty Threat Detection

AWS Certificate Manager and ELB Integration

Amazon S3 Encryption Best Practices

A rate-based rule in AWS WAF is designed to quickly mitigate spikes and potential layer 7 floods bytracking request rates per originating IPand temporarily blocking (or counting/challenging, depending on configuration) IPs that exceed a defined threshold within a 5-minute rolling window. In this scenario, the malicious traffic is distributed acrosshundreds of IPsin two countries, and the application still needs to remain available globally for legitimate users. A rate-based rule provides fast, targeted throttling that reduces abusive request patterns without permanently blocking entire geographies. This aligns with “quickly limit” while minimizing collateral impact.

Blocking both countries with a geo match rule (Option B) would likely block legitimate users located in those countries, which violates the requirement. Security groups (Options C and D) cannot natively enforcegeographicfiltering, and they are not well suited for large, rapidly changing sets of public source IPs at the application layer. Additionally, WAF operates at layer 7 with richer matching (rate limiting, URI/header patterns, bot controls), which is the appropriate control point when the ALB already has a web ACL associated. Therefore, implementing an AWS WAFrate-basedrule is the most effective and least disruptive immediate mitigation.

AWS Organizations tag policies are designed to standardize and govern tag keys and allowed values across accounts. AWS Certified Security – Specialty documentation describes tag policies as a governance mechanism that helps enforce consistent tagging by specifying required tag keys and permitted values. To ensure every resource has the CostCenter tag at creation time, an SCP can deny create actions when aws:RequestTag/CostCenter is missing (null). This prevents resources from being created without the required tag. Tag policies then define the three approved values and can be configured to enforce or report noncompliance depending on supported services, ensuring that tag values remain within the allowed set and preventing drift to unapproved values. Compared with custom Lambda-based enforcement, this approach minimizes operational overhead and keeps enforcement within AWS native governance services. Option A partially addresses allowed values at request time but does not address ongoing governance as cleanly across many services. Option B is not preventive because Lambda runs after events and cannot reliably block all creations. Option D still relies on custom logic and is not as operationally efficient as tag policies plus SCP guardrails.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS Organizations Tag Policies

AWS Organizations SCP Condition Keys for Tag Enforcement

Amazon RDS supports point-in-time recovery (PITR) using automated backups within the configured retention window. According to the AWS Certified Security – Specialty Study Guide, PITR allows recovery to any second within the retention period, making it the most precise recovery method following a security incident.

By restoring the database cluster to a point just before the attack occurred, such as 3:14 PM, the security engineer ensures that the restored database reflects the last known good state without including malicious changes. This method is more accurate than restoring from snapshots, which are created at fixed intervals and may not align with the exact recovery time.

Options B and C rely on snapshot timing and may reintroduce compromised data. Option D restores to an arbitrary time and does not meet the requirement to recover to the last known good version.

AWS documentation explicitly recommends point-in-time recovery for incident response scenarios that require precise restoration.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon RDS Automated Backups and PITR

AWS Incident Response and Recovery Guidance

Amazon GuardDuty provides managed threat detection and supports EKS protection features that analyze Kubernetes audit logs to detect suspicious activity, including unauthorized or unauthenticated access attempts. AWS Certified Security – Specialty documentation recommends GuardDuty for low-overhead detection because it is fully managed and does not require deploying agents or modifying application code. EKS Audit Log Monitoring is designed to consume and analyze relevant control plane audit events to identify anomalous or unauthorized actions against the cluster. Compared to third-party add-ons, GuardDuty reduces operational burden and remains fully within AWS managed services. Security Hub aggregates findings from services like GuardDuty but does not itself perform the detection. CloudWatch Container Insights focuses on performance and operational metrics, not authentication security detections. Therefore, enabling GuardDuty with EKS Audit Log Monitoring provides the required detection with the least operational effort and without requiring additional configuration to the existing EKS workload beyond enabling the feature.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty EKS Protection and Audit Log Monitoring

AWS Threat Detection Best Practices for Kubernetes on AWS

AWS WAF logs contain detailed request-level information, including source IP addresses, requested URIs, and rule matches. According to AWS Certified Security – Specialty guidance, enabling AWS WAF logging provides the most reliable and tamper-resistant method to investigate web-based attacks, especially when instance-level logs are unavailable.

By streaming WAF logs through Amazon Kinesis Data Firehose to Amazon S3, the company ensures durable, centralized log storage that is independent of EC2 lifecycle events. Amazon Athena can then query the logs efficiently to identify repeated requests to the new-user-creation.php endpoint and extract attacker IP addresses.

VPC Flow Logs do not capture HTTP-level details. ALB access logs alone may not capture blocked requests. WAF logs provide the best forensic visibility for future detection.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS WAF Logging and Monitoring

Amazon Athena Log Analysis

Amazon S3 Lifecycle rules are the native and most efficient way to enforce data retention policies. AWS Certified Security – Specialty documentation recommends lifecycle rules over custom automation to reduce operational complexity and failure risk.

Lifecycle rules automatically and reliably delete objects after a specified age, ensuring compliance without additional compute services. Lambda-based solutions increase cost and management overhead. Intelligent-Tiering manages storage cost, not data deletion.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon S3 Lifecycle Management

AWS incident response best practices emphasizerapid containment, credential revocation, and threat detectionto minimize the blast radius of a compromise. According to the AWS Certified Security – Specialty Official Study Guide, when unauthorized resources such as an Amazon S3 bucket hosting malware are discovered, immediate action must be taken to stop further misuse of the account and to prevent recurrence.

Rotating or deleting all AWS access keys (Option D)is a critical containment step. If an IAM user has been compromised, any long-term credentials associated with that user must be revoked immediately to prevent continued unauthorized access. AWS guidance explicitly lists access key rotation or deletion as a first-response action for suspected credential compromise.

Deleting unrecognized or unauthorized resources (Option F)directly removes the malicious infrastructure that is being abused. In this case, deleting the unauthorized S3 bucket immediately stops malware distribution and reduces reputational and compliance impact.

Turning on Amazon GuardDuty (Option B)enables continuous threat detection by analyzing CloudTrail events, VPC Flow Logs, and DNS logs. GuardDuty can identify additional malicious activity, compromised credentials, or persistence mechanisms that the attacker may have established. AWS documentation recommends enabling GuardDuty during or immediately after an incident to detect ongoing or future threats.

Option A does not reduce the impact of the current compromise. Option C is overly disruptive and not recommended; credential rotation should be targeted. Option E is unnecessary because there is no indication that EBS-backed compute resources are involved.

AWS incident response guidance clearly prioritizescredential revocation, malicious resource removal, and threat detectionto minimize consequences.

AWS Certified Security – Specialty Official Study Guide

AWS Incident Response Best Practices

Amazon GuardDuty User Guide

AWS IAM Security Best Practices

The findingInstanceCredentialExfiltrationindicates that credentials available to the EC2 instance (from the instance profile / IMDS) were likely stolen and then used from an unusual location. The fastest way todeny the malicious actor immediatelyis to invalidate the stolen, currently usable credentials. Because these aretemporary credentialsissued to the instance profile role, the correct first containment action is torevoke active sessionsfor that role so the stolen session credentials stop working. This directly blocks continued API use while you continue investigation and remediation.

Changing security groups (Option A) affects inbound network access to the website but does not stop an attacker from using stolen API credentials against AWS APIs. Installing agents and running assessments (Options B and C) are investigative steps that take time and do not immediately cut off the attacker’s current access. After revoking sessions, best practice incident response typically continues with additional containment and eradication steps such as rotating credentials, reviewing CloudTrail for actions taken, checking for persistence (new IAM users/keys, modified policies), patching the instance, and restricting IMDS (for example, enforcing IMDSv2) to reduce risk of further credential theft.

AWS incident response best practices emphasizecontainment with minimal blast radiuswhile preserving business continuity. According to the AWS Certified Security – Specialty Official Study Guide, isolating a compromised resource while allowing the application to continue operating is the recommended initial response.

By creating an Amazon EventBridge rule that reacts to GuardDuty anomalous traffic findings and invokes an AWS Lambda function, the security engineer can automaticallyremove the affected EC2 instance from the Auto Scaling groupand attach arestricted security group. This immediately stops malicious activity while allowing Auto Scaling to replace the instance and keep the application available.

Option A is inappropriate because EC2 instance profiles do not use long-term access keys. Option C applies subnet-wide changes that could disrupt unrelated workloads. Option D provides notification only and does not meet the automated response requirement.

AWS documentation explicitly identifiesinstance isolation via security groupsas a preferred containment technique that preserves application availability and forensic integrity.

AWS Certified Security – Specialty Official Study Guide

Amazon GuardDuty User Guide

AWS Incident Response Best Practices

Before beginning an investigation, incident response best practice is topreserve evidence,prevent accidental loss of the asset, andclearly mark and control the potentially affected resource. Enablingtermination protection(Option B) helps ensure the instance is not accidentally terminated during triage, which would destroy volatile evidence and complicate forensics and recovery.

TakingEBS snapshotsof all attached data volumes (Option C) preserves a point-in-time copy of disk evidence for later forensic analysis, malware scanning, or offline investigation. Snapshots allow responders to create forensic volumes or AMIs in an isolated environment without repeatedly touching the potentially compromised instance.

Capturinginstance metadataand tagging the instance asunder quarantine(Option E) supports both investigation and operational control. Metadata capture (instance ID, IAM role, network interfaces, security groups, user-data, tags, recent changes) provides context for responders. Quarantine tagging enables automated workflows (for example, incident runbooks that isolate the instance, restrict IAM, or move it to a quarantine security group) and signals to other teams/tools that the instance is under investigation.

Option A is the opposite of what you want. Option D destroys evidence. Option F is not an appropriate “before investigation” step; altering metadata risks losing evidence and is not the primary containment approach.

AWS KMS key grants are specifically designed to provide temporary, granular permissions to use customer managed keys without modifying key policies. According to the AWS Certified Security – Specialty Study Guide, grants are the preferred mechanism for delegating key usage permissions to AWS principals for short-term or programmatic access scenarios. Grants allow permissions such as Encrypt, Decrypt, or GenerateDataKey and can be created and revoked dynamically.

Using a key grant avoids the operational risk and overhead of editing key policies, which are long-term control mechanisms and should remain stable. AWS documentation emphasizes that frequent key policy changes increase the risk of misconfiguration and accidental privilege escalation. Grants can be revoked immediately when access is no longer required, ensuring strong adherence to the principle of least privilege.

Options A and D violate AWS security best practices because AWS KMS does not allow direct export of key material unless the key was explicitly created as an importable key, and exporting key material increases exposure risk. Option B requires manual policy changes and rollback, which introduces operational overhead and audit complexity.

AWS recommends key grants as the most efficient and secure way to provide temporary access to KMS keys for applications.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS KMS Key Policies and Grants Documentation

AWS KMS Best Practices

Amazon OpenSearch Service is designed for near real-time log ingestion, indexing, and search across large volumes of data. According to the AWS Certified Security – Specialty Study Guide, OpenSearch supports advanced log analytics use cases and integrates with OpenSearch Security Analytics, which provides prebuilt and custom detection rules.

Security Analytics can continuously evaluate incoming logs from multiple AWS services and generate alerts when detection rules are matched. These alerts can be forwarded to Amazon SNS with minimal configuration. OpenSearch also provides powerful search and query capabilities through APIs and dashboards.

Option C supports detection but lacks advanced correlation and scalable search capabilities. Option B is not a log analytics service. Option D is a visualization service and does not support real-time detection.

AWS guidance recommends OpenSearch Service for centralized, near real-time log analysis and alerting.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon OpenSearch Service Security Analytics

AWS Logging and Monitoring Architecture

The most efficient approach is to useAWS Configbecause Config is designed for continuous compliance evaluation and can automatically triggermanaged remediationwhen a resource drifts from the desired state. A managed Config rule that detects when CloudTrail is not logging, combined with theAWS-EnableCloudTrailremediation action, provides an automated way to re-enable CloudTrail without building and maintaining custom event processing code. This is especially valuable in multi-Region environments because Config can evaluate configurations across Regions and enforce the intended posture consistently.

Option B is illogical: triggering on StartLogging does not help when CloudTrail is turned off. Option C is not as operationally efficient because CloudWatch alarms are not the standard mechanism for reacting to CloudTrail API events; EventBridge is the proper event bus for API call events, but you would still be writing and maintaining Lambda logic and multi-Region plumbing. Option D is manual and delayed, not automated remediation.

Therefore, AWS Config with a managed rule and the AWS-provided remediation to enable CloudTrail is the most maintainable and efficient solution.

The Amazon CloudWatch agent requires explicit IAM permissions to create log groups, create log streams, and put log events into Amazon CloudWatch Logs. According to the AWS Certified Security – Specialty Study Guide, the most common cause of CloudWatch agent log delivery failures is missing or insufficient IAM permissions on the EC2 instance role.

The CloudWatchAgentServerPolicy AWS managed policy provides the required permissions, including logs:CreateLogGroup, logs:CreateLogStream, and logs:PutLogEvents. Attaching this policy to the EC2 instance role enables the CloudWatch agent to successfully deliver custom application logs without requiring changes to the application or logging configuration.

Options A, B, and C are incorrect because CloudTrail, Amazon S3, and Amazon Inspector are not designed to ingest custom application logs from EC2 instances in this manner. AWS documentation clearly states that IAM permissions must be granted to the EC2 role for CloudWatch Logs ingestion.

This approach aligns with AWS best practices for least privilege while ensuring reliable detection and monitoring capabilities.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon CloudWatch Logs Agent Configuration

AWS IAM Best Practices for Monitoring

AWS abuse notifications are delivered as AWS Health events. According to the AWS Certified Security – Specialty Study Guide, Amazon EventBridge integrates natively with AWS Health and can be used to detect specific event types such as AWS_ABUSE_DOS_REPORT in near real time.

By creating an EventBridge rule that filters for the abuse report event type and publishes directly to Amazon SNS, the solution remains fully managed, low latency, and cost effective.

Polling APIs introduces delay and complexity. CloudTrail does not log abuse notifications. EventBridge with AWS Health is the recommended mechanism for reacting to AWS service events.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS Health and EventBridge Integration

AWS Abuse Notification Handling

AWS Systems Manager Session Manager providessecure, auditable, and portless accessto EC2 instances. According to the AWS Certified Security – Specialty Study Guide, Session Manager allows administrators to connect to instanceswithout opening inbound SSH or RDP ports, fully satisfying strict compliance requirements.

Session Manager integrates directly withAWS IAM Identity Center, ensuring that all access is authenticated and authorized using centralized identity management. Additionally, Session Manager automatically records session activity and can send logs to Amazon CloudWatch Logs or Amazon S3, providing a complete audit trail of all commands executed during a session.

Option A (EC2 serial console) does not provide comprehensive auditing and is intended for recovery scenarios. Option B requires inbound network access and security group rules, violating the “no exposed management ports” requirement. Option D explicitly opens ports, which directly violates compliance constraints.

AWS documentation clearly identifiesSystems Manager Session Manager as the recommended solution for secure, auditable, and identity-integrated instance accessin regulated environments.

AWS Certified Security – Specialty Official Study Guide

AWS Systems Manager Session Manager Documentation

AWS IAM Identity Center Best Practices

AWS WAF rate-based rules are designed to help protect applications and resources fromtraffic floods and application-layer DDoS attacksby tracking the number of requests from individual source IP addresses over a rolling time window. According to the AWS Certified Security – Specialty Official Study Guide and AWS WAF documentation, rate-based rules can be configured with different actions, includingCount,Block, andAllow.

When a security engineer is determining an appropriate rate limit that will not block legitimate traffic, AWS best practices recommend initially configuring the rate-based rule with theCountaction. The Count action allows AWS WAF tomonitor and log requests that exceed the specified rate threshold without actively blocking them. This provides visibility into traffic patterns and enables the security engineer to analyze how the rule would behave in production.

By using the Count action, the security engineer can safely evaluate whether legitimate users would be affected by the chosen rate limit. Once the engineer is confident that the threshold accurately distinguishes between normal traffic and malicious behavior, the action can later be changed to Block.

Option B is incorrect because immediately blocking traffic without validation risks denying service to legitimate users. Option C is invalid because AWS WAF does not have a Monitor action. Option D is incorrect because the Allow action does not enforce rate limiting.

AWS documentation explicitly recommendsstarting rate-based rules in Count modeto fine-tune thresholds before enforcing blocks, especially for DDoS protection scenarios.

AWS Certified Security – Specialty Official Study Guide

AWS WAF Developer Guide – Rate-Based Rules

AWS DDoS Resiliency Best Practices

AWS CloudFormation supports the use of aservice role, which allows CloudFormation to assume a dedicated IAM role to create and manage resources on behalf of users. According to the AWS Certified Security – Specialty Study Guide, using a service role is themost secure and consistent wayto ensure predictable stack deployments when users have varying permission sets.

By creating a service role with cloudformation.amazonaws.com as the trusted service principal (Option B), CloudFormation—not individual users—assumes responsibility for resource creation. Updating each stack to explicitly use this service role (Option E) ensures that all deployments use the same permission set, eliminating inconsistencies.

Granting the team members permission to pass the service role via iam:PassRole (Option F) is required so that CloudFormation can assume the role during stack operations. This approach adheres to the principle of least privilege and prevents users from gaining direct access to elevated permissions.

Composite principals (Option A) are unnecessary and insecure. Referencing stack ARNs (Option C) does not solve the root cause. While Option D reflects good policy design, it is implicit in creating the service role and is not a required standalone step.

AWS documentation clearly identifiesCloudFormation service roles combined with iam:PassRoleas best practice for secure, consistent infrastructure deployments.

AWS Certified Security – Specialty Official Study Guide

AWS CloudFormation Service Role Documentation

AWS IAM Best Practices

AWS Systems Manager Session Manager requires secure outbound HTTPS connectivity from the EC2 instance to Systems Manager endpoints. In a VPC without internet access, AWS Certified Security – Specialty documentation recommends using interface VPC endpoints to enable private connectivity without exposing the instance to the internet.

Creating a VPC interface endpoint for Systems Manager allows the SSM Agent to communicate securely with the Systems Manager service. The endpoint must have an attached security group that allows inbound traffic on port 443 from the VPC CIDR range. Additionally, the EC2 instance security group must allow outbound HTTPS traffic on port 443 so the agent can initiate connections.

Option C is incorrect because creating or associating key pairs enables SSH access, which can alter forensic evidence and violates forensic best practices. Option B is unnecessary because Session Manager does not require inbound rules on the EC2 instance. Option F is invalid because EC2 does not use interface endpoints for management connectivity.

This combination ensures secure, private access for forensic investigation while preserving evidence integrity and adhering to AWS incident response best practices.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS Systems Manager Session Manager Architecture

AWS Incident Response and Forensics Best Practices

Amazon Inspector is the AWS service designed specifically for vulnerability management across compute workloads, including Amazon ECR container images and AWS Lambda functions. According to the AWS Certified Security – Specialty documentation, Amazon Inspector provides automated vulnerability assessments for container images stored in ECR by performing enhanced image scanning that identifies common vulnerabilities and exposures (CVEs) in operating systems and application dependencies.

Inspector also supports Lambda code scanning to analyze function packages and container-based Lambda images for known software vulnerabilities. Findings include severity ratings and remediation guidance, allowing security teams to identify and prioritize risks efficiently.

Amazon GuardDuty focuses on threat detection using behavioral analysis and does not perform static vulnerability scanning of container images or Lambda code. AWS Security Hub aggregates findings from other services but does not perform scanning itself.

AWS best practices recommend Amazon Inspector for vulnerability detection in container images and serverless workloads.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon Inspector for ECR and Lambda

AWS Vulnerability Management Best Practices

AWS CloudTrail provides authoritative records of KMS key creation, origin, and usage. Enabling log file validation ensures tamper detection. S3 Object Lock in compliance mode enforces immutability, which is a core audit requirement cited in AWS Certified Security – Specialty materials.

CloudWatch and DynamoDB do not provide immutable storage guarantees suitable for compliance evidence.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS CloudTrail Log File Validation

Amazon S3 Object Lock

Amazon S3 pre-signed URLs grant temporary access based on the permissions of the principal that generates them. AWS Certified Security – Specialty documentation explains that fine-grained authorization can be enforced by combining pre-signed URLs with IAM policy conditions.

By tagging each invoice object with a client identifier and adding a condition to the EC2 instance role policy using s3:ResourceTag/ClientId, the role can generate pre-signed URLs only for objects associated with a specific client. This ensures that each client can access only their own invoices, even though the URLs are temporary and unauthenticated.

Option A over-permissions clients. Option C is unnecessary because instance profiles already use temporary credentials. Option D violates AWS best practices by using long-term credentials.

AWS recommends resource tagging with IAM policy conditions for scalable, secure access control.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon S3 Pre-Signed URLs

IAM Policy Conditions and Resource Tags

AWS WAFrate-based rulesare specifically designed to protect applications from traffic floods and distributed attacks that originate from large numbers of IP addresses. According to the AWS Certified Security – Specialty Official Study Guide, rate-based rules automatically track the number of requests coming from individual IP addresses and temporarily block IPs that exceed a defined threshold.

In this scenario, the malicious traffic originates fromhundreds of IP addresses across two countries, mixed with legitimate user traffic. A rate-based rule allows the security engineer tolimit excessive request rates without fully blocking access from entire geographic regions, ensuring that legitimate users can still access the application.

Option B is incorrect because geographic match rules blockalltraffic from selected countries, which would deny access to legitimate users and violate the stated requirement. Option C is invalid because security groups do not support geographic filtering. Option D is not scalable, as manually blocking hundreds of IP addresses is operationally inefficient and ineffective against rapidly changing attacker IPs.

AWS documentation emphasizes thatrate-based rules are the recommended first-line mitigationfor sudden traffic spikes and potential application-layer DDoS attacks when business continuity must be preserved.

AWS Certified Security – Specialty Official Study Guide

AWS WAF Developer Guide – Rate-Based Rules

AWS DDoS Resiliency Best Practices

Amazon Detective is a purpose-built AWS service designed toanalyze, investigate, and visualize security datato help identify the root cause of suspicious or malicious activity. According to the AWS Certified Security – Specialty Official Study Guide, Amazon Detective directly integrates withAmazon GuardDuty findings, AWS CloudTrail logs, Amazon VPC Flow Logs, and Amazon EKS audit logs to automatically create behavior graphs and timelines.

When GuardDuty generates findings related to anomalous activity, Amazon Detective enables security engineers to pivot directly to an investigation focused on a specific IAM role, user, or resource. Detective automatically correlates historical activity, identifies deviations from baseline behavior, and highlightsindicators of compromise, such as unusual API calls, credential misuse, or suspicious network activity.

AWS Audit Manager (Option B) is designed for compliance and audit evidence collection, not threat investigation. Amazon Inspector (Options C and D) is focused on vulnerability scanning of compute resources and does not analyze IAM behavior or GuardDuty findings.

AWS documentation explicitly states thatAmazon Detective is the recommended service for deep-dive investigations following GuardDuty alerts, providing enriched context and investigation reports for security incidents.

AWS Certified Security – Specialty Official Study Guide

Amazon Detective User Guide

Amazon GuardDuty Integration Documentation

EC2 Instance Connect can performserver/host authenticity checksby validating the instance’s SSHhost keyagainst atrusted host keyssource. When you rotate the instance’s host keys, the host presents anewfingerprint. If the trusted host keys source still contains theoldhost key, connections that enforce host key verification will fail with ahost key validationerror. The fix is to update the trusted host key record so the new host key fingerprint is recognized as valid. Therefore, the correct action is toupload the new host keyto the trusted host keys database used for EC2 Instance Connect host key verification.

Option A is unrelated: AWS KMS does not store or manage SSH host keys for EC2 Instance Connect validation. Option C is for AWS Systems Manager managed instances and has no effect on SSH host key validation. Option D rotatesuser/client authentication keys(SSH key pair used to log in) but does not resolve a failure that occurs specifically because theserver host keychanged and is no longer trusted. Updating the trusted host keys database restores the expected trust chain and allows Instance Connect to work again with the rotated host keys.

AWS KMS access control is primarily enforced through key policies (and optionally grants), and AWS recommends using key policy condition keys to restrict how keys can be used. The kms:ViaService condition key is specifically designed to restrict KMS API usage to requests that come through a particular AWS service endpoint in a specific Region. This is the most robust way to ensure a key can be used only via AWS Lambda (for example, lambda. < region > .amazonaws.com) and not via Amazon EC2 (ec2. < region > .amazonaws.com), even if IAM permissions exist elsewhere. By writing a key policy that uses the Lambda execution role as the principal and conditions on kms:ViaService, the company can tightly bind key usage to Lambda-originated cryptographic operations while preventing use through EC2 service paths. Option A is weaker because EC2 is not the only way an IAM principal might use KMS, and relying on attaching explicit deny policies broadly is harder to manage and can miss principals. Option C is incorrect because aws:AuthorizedService is not the typical mechanism for KMS service restriction, and SourceIp is unreliable for service-to-service calls. Option D is not ideal because SCPs do not provide fine-grained service-path restrictions for KMS usage and cannot “allow” beyond IAM; key policy controls still apply.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS KMS Key Policies and Condition Keys

AWS KMS Best Practices for Service-Scoped Key Usage

Amazon Cognito threat protection is purpose-built to detect and mitigate malicious authentication activity such as credential stuffing and bot traffic. It uses adaptive risk-based analysis without disrupting legitimate users.

AWS WAF cannot be directly associated with Cognito user pools.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

Amazon Cognito Threat Protection

The requirement is to havekey material generated and used inside a custom key store backed by an AWS CloudHSM cluster. This is exactly whatAWS KMS Custom Key Storesprovide: KMS manages the keys and policies, but the cryptographic operations for those KMS keys occur in the associatedCloudHSMcluster, keeping the key material within HSM boundaries. For applications that needlocal-use data keys(both symmetric data keys and asymmetric data key pairs), KMS supports generating data keys and data key pairs that applications can use for envelope encryption and local cryptographic operations, while the master key protections remain within KMS (and within CloudHSM when using a custom key store).

For auditing, AWS best practice isAWS CloudTrail, which records KMS API calls (such as CreateKey, GenerateDataKey, GenerateDataKeyPair, Encrypt/Decrypt, etc.) and provides an immutable event history for compliance and investigation. Athena can query logs, but it is not the primary audit record source; GuardDuty is for threat detection, not authoritative key-usage auditing. Therefore, the correct combination isKMS with a CloudHSM-backed custom key storeplusCloudTrailfor auditability.

AWS Key Management Service (KMS) customer managed keys areregional resources. According to the AWS Certified Security – Specialty Official Study Guide and KMS documentation, a KMS key created in one AWS Regioncannot be used directly in another Region. When copying an encrypted Amazon Aurora DB snapshot across Regions, the destination Region must have access to a KMS keythat exists in that Region.

Because the original KMS key resides in us-east-1, it cannot be accessed or referenced in us-west-1. The correct and supported approach is tocreate a new customer managed KMS key in us-west-1and specify that key when performing the cross-Region snapshot copy. Amazon RDS automatically decrypts the snapshot using the source Region key and re-encrypts it using the destination Region key during the copy process.

Option A is invalid because KMS keys cannot be stored or transferred through AWS Secrets Manager. Options C and D are incorrect because IAM policies cannot grant cross-Region usage of a KMS key; KMS enforces strict regional boundaries regardless of IAM permissions.

AWS documentation clearly states thatcross-Region encrypted snapshot copies require a KMS key in the destination Region, making this approach mandatory for compliance and encryption continuity.

AWS Certified Security – Specialty Official Study Guide

AWS Key Management Service Developer Guide

Amazon Aurora Security Documentation

The fastest, least-effort way to mitigate SQL injection at the edge—without modifying legacy application code—is to place the application behind a component that supportsAWS WAFand applymanaged SQL injection protections. AnApplication Load Balancerintegrates directly with AWS WAF, allowing the security engineer to deploy a web ACL (including AWS Managed Rules for SQL injection and custom patterns based on the provided samples) and immediately start blocking malicious payloads before they reach the EC2 instances and the database.

Option A also preserves normal operations during rollout: you can create the ALB, register the existing EC2 instances as targets, validate health checks and traffic behavior, apply WAF protections, and then shift Route 53 weighted records to the ALB with minimal downtime. Finally, tightening the EC2 security groups to prevent direct internet access ensures all inbound web traffic is forced through the ALB + WAF inspection point, reducing exposure quickly.

Option B is risky because it uses only one EC2 origin (reducing availability) and adds CloudFront origin configuration complexity under a 24-hour deadline. Option C requires code changes on unsupported software and is unlikely to be safely delivered in time. Option D is invalid because AWS WAF cannot be attached directly to EC2 instances, and changing DB-port exposure doesn’t address SQL injection on the web layer.