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Incident Response Plan for Beginners (First 24 Hours)

By , Cyber Security trainer LinkedIn Published: Last updated:

An incident response plan for beginners focuses on the first 24 hours: stay calm, identify what happened, contain spread, preserve evidence, eradicate what you can, recover from known-good backups, and write down lessons. Follow a written checklist so panic does not delete the logs you need.

Friends, "Server got hacked!" — the first reaction is panic delete. Wrong. NIST-style lifecycle: Identify → Contain → Eradicate → Recover → Lessons. Today a beginner plan for the first 24 hours in vertical steps. US teams often align with NIST SP 800-61 ideas; small teams can still use the same order.

Quick answer

First-day order:

  1. Declare — name an owner; start a timeline doc (UTC and local).
  2. Identify — what systems, what symptoms, when first seen, who reported.
  3. Contain — isolate affected hosts / revoke sessions / block indicators (do not destroy evidence).
  4. Preserve — volatile notes, key logs, disk snapshots as your role allows.
  5. Eradicate — remove malware / close the exposed hole with a verified fix.
  6. Recover — restore from clean backups; monitor closely.
  7. Communicate — users, leadership, customers as policy requires; consider legal / cyber-insurance contacts.
  8. Lessons — one-page write-up within a few days while memory is fresh.

Tiny incident log template:

Date/time (IST / local):
Owner:
Systems affected:
Suspected entry path:
Containment actions + time:
Evidence collected:
Recovery actions:
Next check-in time:

What do I need before this guide?

  • A one-page contact list (IT lead, hosting provider, domain registrar, legal if any).
  • Backups you have tested (ransomware guide).
  • Optional deeper course lessons on SOC / IR lifecycle.

What does the first 24 hours look like?

Incident response first 24 hours Identify, contain, eradicate, recover, then write lessons learned. Speed with calm beats panic. Identify Contain Eradicate Recover Lessons NIST-style lifecycle — first day focus: identify + contain

First 24 hours follow identify, contain, eradicate, recover and lessons — keep a timeline and do not panic-wipe the evidence.

  1. Morning hour 0–2: identify and contain the blast radius.
  2. Hours 2–8: preserve evidence; reset identity systems if accounts are in play.
  3. Hours 8–24: eradicate, begin recovery, communicate clearly, schedule lessons-learned.

Exact timing varies — the order matters more than the clock.

How do I run the first 24 hours?

Step 1 — Identify (hour 0)

  1. Write the symptom in one sentence.
  2. List affected users, hosts, domains and cloud accounts.
  3. Capture “first seen” and “last normal”.
  4. Decide severity (one laptop vs domain admin vs customer data).

Step 2 — Contain without wiping everything

  1. Disconnect or network-isolate clearly affected endpoints.
  2. Disable compromised accounts; revoke API keys and sessions.
  3. Block known-bad IPs/domains at email / proxy / firewall if you trust the indicators.
  4. Avoid mass reimaging before snapshots if forensics or insurance may need evidence — follow your org policy.

Step 3 — Preserve evidence

  1. Note exact times and commands/actions you take.
  2. Export relevant logs (auth, VPN, mail, cloud audit) to write-once storage when possible.
  3. Snapshot VMs / volumes before major rebuilds when practical.
  4. Do not run random “cleaner” tools that scramble timelines on critical boxes.

Step 4 — Eradicate the cause

  1. Patch or reconfigure the exposed service.
  2. Remove persistence you found (unusual tasks, new admin users, mail forwarding rules).
  3. Rotate credentials that might have been stolen — email first for many small teams.
  4. Confirm MFA enrollment on rebuilt identities.

Step 5 — Recover and watch

  1. Restore data from a backup taken before the incident.
  2. Bring services up in stages; verify integrity checks.
  3. Heighten monitoring for 24–72 hours.
  4. Keep the incident channel open until exit criteria are met.

Step 6 — Communicate and learn

  1. Send factual updates (what you know, what you are doing, next update time).
  2. Avoid speculation in customer emails.
  3. Schedule a short lessons-learned meeting.
  4. Turn one finding into a permanent control (MFA, backup drill, firewall rule, alert).

Ravindra Bagale's Tip

💡 Panic format-c: wipes logs and proof. First rule: write the timeline, contain, preserve evidence. A notepad is enough for a solo learner. On a team, one owner — "too many cooks" makes it worse. Never forget!

How do I fix common first-day IR mistakes?

Ghabru naka 😅 — these are the usual ones:

Symptom Likely cause Fix
No idea what changed No timeline Start the incident log immediately; interview reporters
Attacker still creating users Containment incomplete Isolate identity plane; revoke sessions/keys
Restored, reinfected Backup after compromise / hole still open Fix root cause first; pick older clean backup
Users confused No communication owner Hourly or twice-daily factual updates
Repeated incident No lessons → control One permanent hardening item before closing

Try it at home

Tabletop only (no real breach needed). Pick a scenario: “finance laptop ransomware note”. Write your first 12 actions as a vertical numbered list with owners and times. Compare with this guide’s order.

Learn it properly

Got it? First 24h: identify, contain, preserve, eradicate, recover, communicate, lessons. No panic wipe. Timeline + owner + clean backup. Complete the plan with the related phishing and ransomware guides.

Frequently asked questions

What should I do first in an incident?

Name an owner, start a timeline, identify what is affected, then contain without destroying evidence.

Why not format the disk immediately?

You may wipe the logs and proof you need for recovery, insurance or law enforcement. Contain first; image when required.

What framework is this aligned with?

A beginner-friendly reading of common IR phases similar to NIST-style identify/contain/eradicate/recover/lessons.

What if backups are also bad?

Pick an older clean restore point and fix the entry path before bringing systems fully back.

Who should I call?

Your pre-written contact list: IT lead, hosting provider, and legal/insurance if applicable.

Where are deeper lessons on this site?

Cyber SOC/SIEM/IR chapters and malware incident-response lessons.