Introduction to Forensics Acquisition and Triage

Introduction to Forensics Acquisition and Triage

Forensics acquisition and triage are foundational aspects of digital forensics and incident response, focusing on the systematic collection, preservation, and initial analysis of digital evidence.

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Key Concepts

Forensics Acquisition

• Purpose: To create an exact, bit-by-bit copy of data from storage devices or memory.

• Goals:

  • Capture all data, including active files, deleted data, hidden files, and volatile memory.

  • Maintain integrity for legal admissibility.

• Popular Acquisition Tools:

  • FTK Imager: Used for disk imaging and file previewing.

  • Magnet RAM Capture: Captures memory from live systems.

  • Belkasoft Live RAM Capture: Acquires volatile memory.

  • AVML (Accelerated Volatile Memory Locator): Lightweight memory capture tool for Linux.

Triage

• Purpose: To quickly identify and analyze relevant data from acquired evidence.

• Goals:

  • Prioritize analysis based on immediate threats or key leads.

  • Filter through data using keywords, file types, and other parameters.

• Popular Triage Tools:

  • KAPE (Kroll Artifact Parser and Extractor): Collects and parses forensic artifacts rapidly.

  • FireEye Redline: Focuses on memory and file system analysis for advanced threat detection.

  • Volatility: Extracts and analyzes data from memory dumps.

  • Autopsy: Open-source forensic platform for file system and artifact analysis.

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Key Considerations

• Data Integrity:

  • Use hashing (e.g., MD5, SHA-1) to validate the integrity of acquired data.

  • Ensure no tampering occurs during acquisition.

• Chain of Custody:

  • Document every step of the evidence handling process.

  • Include details about the person handling the evidence, time of acquisition, and methods used.

• Minimal System Interaction:

  • Run acquisition tools in a non-invasive manner.

  • Preferably execute tools from external devices (USB drives) or remote locations.

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Scenario: Compromised Production Server

Detection Phase:

• Incident: The SOC team detects unusual traffic patterns from a production server.

• Alert: An alert is escalated to the forensics team.

Acquisition Phase:

• Disk and Memory Capture:

  • FTK Imager is used to create a forensic disk image.

  • Belkasoft Live RAM Capture captures volatile memory.

• Integrity Validation:

  • Hashes (MD5/SHA-256) are computed before and after acquisition to ensure the data remains unaltered.

Triage Phase:

• Rapid Artifact Collection:

  • KAPE is run to collect registry hives, event logs, and browser history.

• In-Depth Analysis:

  • FireEye Redline scans for indicators of compromise (IOCs), focusing on memory and file system anomalies.

  • Volatility is used to inspect memory dumps for active malware, suspicious processes, and network connections.

• Findings:

  • Evidence of a phishing email leading to malware installation.

  • Persistent malware communicates with external C2 servers.

  • Data exfiltration detected over an extended period.

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Response Actions

• Containment:

  • The compromised system is isolated from the network.

  • Malware is quarantined and removed.

• IOC Correlation:

  • IOCs (IP addresses, file hashes) are shared with the SOC to scan other systems.

  • Additional compromised endpoints are identified and isolated.

• Remediation:

  • Vulnerabilities exploited by the attacker are patched.

  • Security controls are strengthened, such as improved email filtering and user training.

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Key Tools Overview

Tool	Purpose	Platform
FTK Imager	Disk imaging and previewing	Windows
Belkasoft RAM Capture	Memory acquisition	Windows
AVML	Lightweight memory acquisition	Linux
KAPE	Rapid artifact collection and parsing	Windows
FireEye Redline	Memory and file system analysis	Windows
Volatility	Memory forensics	Cross-Platform
Autopsy	Comprehensive forensic analysis	Windows/Linux

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Best Practices

• Preserve Evidence Integrity:

  • Always verify acquired data with hashing.

  • Use write-blockers when acquiring disk images.

• Minimize Impact:

  • Avoid changes to the live system during acquisition.

  • Use trusted acquisition tools with minimal system footprint.

• Maintain Documentation:

  • Ensure comprehensive documentation of all steps, from acquisition to analysis.

  • Maintain detailed chain-of-custody records to ensure legal admissibility.

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Key Points

Forensic acquisition and triage form the backbone of digital investigations. Leveraging robust tools and adhering to best practices ensures that investigators can efficiently collect and analyze evidence while maintaining its integrity.