HPE7-A02 Forensics

Forensics Detailed Explanation

Digital forensics in a network context refers to the process of collecting, analyzing, and preserving evidence of security events or incidents. It’s a critical skill for investigating attacks, policy violations, or misbehavior inside your network.

1. Evidence Gathering

When an incident occurs (e.g., a rogue device connected, data was exfiltrated, or malware spread), you need to collect solid, timestamped, verifiable evidence. Aruba provides multiple ways to do this:

Tech-Support Bundle

• Aruba devices (switches, gateways, APs) allow you to collect all relevant data in one command:

  • Logs

  • Packet captures (PCAPs)

  • Running configuration

  • Interface stats

Command example (AOS-CX):

copy support-save usb:/TS.tgz

Or send to a remote SCP server:

copy support-save scp://[email protected]:/backups/TS-SwitchA.tgz

Why it matters:

• A snapshot of the system's state at the time of incident.

• Essential for offline analysis and legal compliance.

ClearPass Audit Trail

• Every action in ClearPass is:

  • Logged

  • Timestamped

  • Digitally signed

• This includes:

  • Admin logins and configuration changes

  • Authentication attempts

  • Enforcement decisions (e.g., CoA, quarantine)

Use case: Helps identify who changed what and when — crucial in investigations involving human error or malicious insider activity.

Aruba Central Alert Export

• Aruba Central generates alerts and logs that can be:

  • Downloaded

  • Exported with a hash-check manifest

• The manifest includes SHA-256 or SHA-512 hashes to prove the file wasn't altered — this ensures chain of custody, a legal standard for forensic evidence.

Why it matters:

• You can present this data as evidence in legal or compliance audits.

2. Timeline Reconstruction

After gathering evidence, the next step is to piece together what happened, when, and in what order.

Correlate Authentication Logs, Flow Data, and SIEM Events

• Use timestamps from:

  • RADIUS logs (ClearPass authentication and CoA times)

  • NetFlow/IPFIX (shows who connected where, for how long)

  • SIEM alerts/logs (e.g., failed login attempts, anomalous behavior)

Key requirement: All systems (switches, ClearPass, Central, SIEM) must be synced to the same NTP server to avoid timestamp mismatches.

Example:

• A device authenticates at 08:30.

• Sends 100MB to an external IP from 08:32 to 08:35.

• A security alert is triggered at 08:36.

This correlation builds a reliable timeline.

Certificate Validation (OCSP/CRL)

• If a certificate was revoked or expired, it could lead to failed authentication or an impersonation attempt.

• Aruba ClearPass checks:

  • OCSP (Online Certificate Status Protocol) — live certificate status check.

  • CRL (Certificate Revocation List) — downloaded list of revoked certs.

Use case: If an attacker tries to reuse an old certificate, OCSP/CRL logs will show that the cert was invalid at the time.

3. Post-Incident Actions

Once the incident is resolved, you must strengthen the network to prevent it from happening again. Forensics isn't just about solving yesterday’s problem — it's about improving tomorrow’s security.

Update ClearPass Profiler Fingerprints

• ClearPass Device Insight uses fingerprints to classify devices.

• If a new type of rogue device was involved, update or fine-tune the fingerprint so similar devices are flagged in the future.

Adjust Enforcement Logic

• Modify ClearPass enforcement policies based on behavior:

  • Apply stricter roles to risky device categories.

  • Limit access for vendors or third-party devices during off-hours.

  • Auto-quarantine devices showing suspicious traffic or posture failures.

Example: Block access to financial servers for non-corporate devices, even if they pass 802.1X.

Enable CoPP & Update IDS Signatures

• If a flood or scan caused the issue:

  • Tighten Control Plane Policing (CoPP) to rate-limit more protocols (ICMP, BGP, LLDP).

• If malware was missed:

  • Update IDS/IPS signatures on Aruba EdgeConnect or your firewall.

4. Summary

Task	Tool or Technique	Purpose
Gather evidence	support-save, ClearPass audit trail	Freeze data for analysis
Maintain integrity	Hash-check manifests	Prove files are unaltered
Correlate events	NTP-sync, log analysis	Build a clear timeline
Prevent recurrence	Adjust roles, update signatures	Strengthen network security

Forensics (Additional Content)

1. Forensic Evidence Export from Aruba Central

When responding to a security incident, one of the most important steps is exporting logs and traffic data with integrity verification.

Aruba Central: Manual Export with Hash Validation

Export Path:

1. Navigate to Aruba Central Dashboard

2. Go to Events & Alerts > System Events or Clients > Client Session Logs

3. Use Filters (time, client MAC, site) to narrow down relevant data

4. Click “Export” → “Include Hash Manifest”

5. Choose format (e.g., CSV, JSON) and download:

   • You’ll receive:

     • The data file (e.g., client_logs.csv)

     • A manifest file (e.g., client_logs_manifest.sha256)

     • Optional metadata (e.g., export_meta.json)

Purpose of Hash Manifest:

• Contains SHA-256 or SHA-512 checksum

• Allows validation that logs were not tampered with post-export

• Critical for legal chain of custody in investigations

Example:

File: client_logs.csv
SHA-256: a4d9f3080ed2a1295c4040e99c08d884fa78b4b3c4d30b12570f5b04eb5c2f76

Use a hash tool (e.g., sha256sum) to revalidate exported file at any time.

2. ClearPass Audit Trail Log – Example Output

The Audit Trail in ClearPass tracks all administrative and system-level actions. It is timestamped and digitally signed for integrity.

Use Case:

Track changes during an insider breach investigation or misconfiguration event.

Sample Entry (CLI or Web Export):

{
  "timestamp": "2025-04-13T14:23:56Z",
  "admin": "j.smith",
  "action": "Updated Enforcement Profile",
  "target": "Role_Quarantine",
  "client_ip": "10.25.4.77",
  "auth_method": "Web UI",
  "signature": "Valid"
}

Key Fields:

• timestamp: UTC time of the action (NTP-synced)

• admin: Operator or system account performing the action

• action: What was changed or triggered

• target: Name of object affected (role, profile, policy)

• signature: Digital hash to prevent log tampering

Access Path in GUI:

ClearPass Policy Manager > Administration > Audit Viewer

• Filter by admin, time, or action type

• Export as CSV or JSON for external review

Summary

Topic	Benefit	Aruba Tool
Manual Export from Aruba Central	Ensures legally admissible logs with cryptographic validation	Log Export + Hash Manifest
Audit Trail Sample Format	Aids exam questions and practical investigations	ClearPass > Audit Viewer
Structured Evidence Tracking	Supports timeline reconstruction and compliance	Time-synced logs, verifiable output