CHFI (312-49) Digital Forensics Simulation

In this simulation, you will learn the correct forensic procedure for preserving evidence from a compromised virtual machine in a cloud environment. Mastering the evidence collection phase in Microsoft Azure is critical for maintaining data integrity during incident triage.

Investigation Scenario

GlobalCorp's security monitoring alerted on rapid file encryption patterns originating from an Azure Virtual Machine named azure-ubuntu located in the Production-group resource group. As the lead forensic investigator responding to this ransomware incident, your immediate objective is to securely acquire the VM's OS disk for offline analysis.

You must perform this preservation task strictly using the Azure Portal GUI according to the incident triage playbook, ensuring that the evidence is captured as a read-only entity without inadvertently altering the potential active state or violating the sequence of collection.

Evidence Collected (Pre-Triage)

[+] Alert ID: AZ-SEC-9921 (Ransomware Behavior Detected)
[+] Target Resource: azure-ubuntu (Ubuntu Server 20.04 LTS)
[+] Resource Group: Production-group
[+] Disk Target: OS Disk (Premium SSD)
[+] Investigator Constraint: Utilize Azure Portal GUI

Question

Question 9: During a ransomware triage in a Microsoft Azure environment, forensic analysts are instructed to preserve evidence from a compromised azure-ubuntu virtual machine by creating a snapshot of its OS disk through the Azure Portal. Which of the following sequences accurately completes this task?

Investigator Hint: Read the scenario constraints carefully. You are tasked with using the Azure Portal. Also, consider the impact of "stopping" a VM during a ransomware investigation before memory acquisition has taken place.

Expert Analysis

1. What the Evidence Shows

The scenario outlines a ransomware infection on a live Azure VM. The primary requirement is to execute the preservation of the OS disk using the Azure Portal without compromising the current state of the machine or deviating from standard GUI procedures.

2. Forensic Stage

Preservation and Collection. Securing a bit-for-bit or point-in-time representation of the storage media ensures that subsequent analysis is performed on a copy, maintaining the integrity of the original evidence.

3. Why the Correct Answer is Correct (Option C)

Option C accurately outlines the direct, step-by-step process for creating a read-only snapshot of an OS disk directly through the Azure Portal. By selecting "read-only," the investigator ensures the snapshot cannot be modified, which is a critical requirement for maintaining digital evidence integrity before hashing and exporting the disk for examination.

4. Why Others Are Wrong

Option A: Involves deleting the snapshot from the source group. Destructive actions or unnecessary data movement before secure backups are hashed and verified violate the chain of custody and introduce high risks of data loss.

Option B: Instructs the investigator to "Stop the azure-ubuntu VM" first. While stopping a VM ensures file system consistency, it immediately destroys volatile memory (RAM). In a ransomware triage, RAM may contain crucial artifacts like encryption keys or active network connections. If memory hasn't been acquired yet, stopping the VM is premature.

Option D: Utilizes the Azure CLI. While technically a valid way to create a snapshot, the scenario explicitly dictates that the task must be completed "through the Azure Portal."

5. Real-World Forensic Action

In a live incident, an investigator will generate the read-only snapshot of the affected disk. Subsequently, a forensic workstation (often an isolated VM within a secure Azure subscription) is deployed. The snapshot is used to create a new managed disk, which is then attached to the forensic workstation in read-only mode for timeline analysis, file carving, and malware extraction using tools like Autopsy or FTK Imager.

6. MINI LESSON: Cloud Evidence Handling

• Artifact Interpretation: Cloud snapshots represent a point-in-time crash-consistent state of the disk.
• Chain of Custody: When exporting the snapshot to a VHD file for local analysis, forensic hashes (SHA-256) must be generated immediately upon download to prove the file matches the state of the snapshot in the cloud.
• Forensic Workflow: Always prioritize volatile data (RAM, active connections) before non-volatile data (Disks). Capturing a live snapshot allows disk preservation to begin without immediately sacrificing volatile artifacts by powering down the system.

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