Baseline in Digital Forensics

A baseline is a captured snapshot of a system's normal state under known-good conditions. It records what processes, services, network connections, user accounts, firewall settings, and other artifacts look like when the system is operating normally.

Why baselines matter

In forensic analysis, "normal" is not universal. A service, scheduled task, or open port that looks suspicious on one machine might be standard business software on another. Without a baseline, every investigation starts blind: analysts must guess whether an artifact is malicious or benign.

A baseline removes that guesswork by providing a reference point. Future snapshots are compared against it to identify:

• New or missing processes and services
• Unexpected network connections or listeners
• New user accounts or group memberships
• Firewall or defender configuration changes
• Unusual event log patterns

Practical use with PowerShell

PowerShell CmdLets like Get-Process, Get-Service, Get-NetTCPConnection, Get-LocalUser, Get-MpComputerStatus, and Get-EventLog can acquire the raw state. The output is stored, formatted, or serialized. Later acquisitions are compared against the baseline using Compare-Object or exported to Python for analysis.

Key principle

A service that looks suspicious on one system might be standard on another.

This is why baseline-driven comparison is more reliable than static lists of "bad" indicators. Context — the specific machine, its role, and its normal behavior — determines whether an artifact is evidence of compromise or everyday noise.

Best practices

• Capture the baseline from a clean, trusted state
• Store it securely and treat it as read-only reference data
• Record date, time, and system identity with the baseline
• Re-acquire periodically rather than just once
• Use versioned baselines if the system's role changes over time