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30. Cloud and AWS Security

30.5 Detection: CloudTrail, GuardDuty, Config and Security Hub

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Quick answer: the short, self-contained version of this lesson is the guide AWS Security Best Practices Checklist.

You cannot defend what you cannot see. AWS gives four key detection services:

Service What it does Think of it as
CloudTrail Records every API call: who did what, when, from which IP The account's CCTV recording
GuardDuty Analyses CloudTrail, VPC Flow Logs and DNS logs to spot threats (crypto-mining, calls from known bad IPs, unusual logins) An automatic security guard
AWS Config Tracks configuration changes and checks rules like "no public S3" or "EBS must be encrypted" A compliance checklist that runs itself
Security Hub Collects findings from GuardDuty, Config, Inspector and more into one dashboard with best-practice scores The control room

Minimum setup for any real account:

  1. Create a multi-region CloudTrail trail that writes to a dedicated S3 bucket (with Block Public Access and versioning on).
  2. Enable GuardDuty and send high-severity findings to your email through EventBridge and SNS.
  3. Keep a billing alarm (Chapter 12) – a sudden bill spike is often the first sign of stolen keys.
  4. Turn on VPC Flow Logs for the VPC to see accepted and rejected network traffic.
# Who deleted something recently? Look up events in CloudTrail
aws cloudtrail lookup-events --lookup-attributes AttributeKey=EventName,AttributeValue=DeleteBucket --max-results 5
# Any console logins without MFA?
aws cloudtrail lookup-events --lookup-attributes AttributeKey=EventName,AttributeValue=ConsoleLogin --max-results 10

Ravindra Bagale's Tip

If CloudTrail is not turned on, after a hack you will never know "what happened". Logs are the first piece of evidence in an investigation. Set up the trail and a billing alarm on the day you open the account – not later.

Lab

Create a multi-region trail. Make a harmless change (create and delete an empty test bucket), then find both events in CloudTrail Event history and note the user, time and source IP. If you enable the GuardDuty free trial, open Settings, Generate sample findings and read three findings. Disable anything you will not keep after the lab.

Extended teaching notes

Why this lesson matters

Cloud security is mostly IAM, network exposure, logging and secure defaults. The shared responsibility model means the provider patches the metal; you patch what you configure.

  • No public databases or public admin panels.
  • Roles / OIDC instead of long-lived access keys.
  • CloudTrail / Activity Logs / Audit Logs on and retained.
  • S3/Blob/GCS: Block Public Access; encrypt; least privilege.

Mini case study

Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.

Defender's worksheet (do this today)

  1. Write the lesson title, date and the exact lab target you are allowed to use.
  2. List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
  3. Run one safe check from the lesson on a lab system only. Paste the command and output.
  4. Write a two-sentence fix you would give a teammate.
  5. Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.

Indian workplace (sample data)

Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).

Global practice

Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.

Everyday analogy

Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.

Key terms

  • Control: a safeguard (patch, config, process, detection).
  • Finding: a weakness backed by evidence.
  • Remediation: the fix plus how you verified it.
  • Scope: systems you have written permission to touch.
  • Least privilege: only the access the task needs.
  • Defence in depth: several layers so one failure does not end the story.

Common mistakes

  • Skipping written permission "just for a quick scan".
  • Practising on hostel, office or public targets without authorisation.
  • Collecting tool output without writing the fix.
  • Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
  • Publishing screenshots that contain secrets, cookies or internal hostnames.

Recap

  • Evidence, fix, owner, date.
  • Own lab only.
  • Fix > spectacle.