Acquisition Strategies

Acquisition strategies in computer and cyber forensics outline systematic approaches to capturing digital evidence from diverse sources, balancing completeness, volatility, and practicality to ensure forensically sound results.

These strategies adapt to system states, hardware types, and incident urgency, prioritizing data that risks loss while maintaining chain of custody throughout.

Proper selection prevents evidence gaps or contamination, enabling reliable reconstruction in investigations ranging from ransomware responses to legal probes.

Principles Guiding Acquisition Strategy Selection

Strategy choice depends on data volatility, access constraints, and legal requirements.

Note: High-volatility data demands immediate capture; stable data allows methodical imaging.

Core Factors Include:

1. Volatility hierarchy: RAM > network state > running processes > disk data.

2. System state: Live (running) vs. dead (powered off).

3. Storage type: HDD persistence vs. SSD TRIM risks.

4. Scale: Single endpoint vs. enterprise fleet.

5. Legal posture: Full imaging for court vs. triage for IR.

Document rationale for defensibility.

Full Disk Imaging (Dead Acquisition)

Bit-for-bit copies preserve all sectors, including deleted/unallocated space.

Note: Gold standard for legal cases; requires physical access and time.

Process: Connect via write-blocker → Image → Hash verify → Store securely. Handles RAID by imaging members identically.

Live Acquisition for Volatile Data

Captures running system state without shutdown, preserving ephemeral evidence.

Note: Essential for servers/enterprises where reboot loses RAM or connections.

1. Memory acquisition: Volatility, Belkasoft RAM Capturer dump physical memory for processes/malware.

2. Agent-based collection: Velociraptor, GRR deploy scripts pulling processes, network tables, registry hives.

3. Minimal footprint: Run read-only scripts; avoid installs that alter timestamps.

4. Sequence: RAM → Processes → Network → Selective files → Shutdown for disk imaging.

Logical and Targeted Acquisition

Extracts accessible data without full imaging, suitable for large/encrypted volumes.

Note: Faster for mobiles/cloud; supplements full acquisition.

Limitations: Misses deleted data; use when full imaging infeasible.

Enterprise and Remote Acquisition Strategies

Scales to distributed environments with automation.

Note: Agents enable mass collection across fleets without physical access.

Centralize to SIEM for triage; respect retention policies.

Specialized Acquisition Scenarios

Addresses edge cases with tailored methods.

Note: Failing hardware or encryption demands urgency and alternatives.

1. Damaged drives: ddrescue skips bad sectors progressively; chip-off for dead NAND.

2. Encrypted volumes: RAM dumps for keys; bypass via cold boot if powered recently.

3. Virtual environments: Export VM snapshots, hypervisor logs (VMware .vmdk).

4. IoT/embedded: JTAG/chip-off; firmware dumps via specialized hardware.

Always validate with hashes; document limitations (e.g., "15% sectors skipped").

Verification and Post-Acquisition Workflow

Confirms acquisition soundness before analysis.

Note: Multiple checks build chain of custody.

1. Compute source/copy hashes immediately.

2. Cycle consistency tests (read image back).

3. Peer verification signatures.

4. Secure vault storage with access logs.

Common pitfalls: Incomplete volatiles, unhashed transfers, ignoring encryption state. Modern tools automate workflows, but strategy remains human-driven for 2025 complexities.