45. Practice Exercises with Hints
45.8 Cloud, SOC, Hardening and Crypto – Mixed Drill
IAM least privilege, CloudTrail/GuardDuty awareness, fail2ban, firewalld, SSH keys, hashing vs encryption, TLS 1.2+.
| Exercise | Task | Hint |
|---|---|---|
| E1 | Write IAM policy idea: EC2 read-only S3 one bucket | Resource ARN scoped; no * on sensitive actions |
| E2 | Name three log sources a tiny SOC wants first | Auth logs, web access, CloudTrail / VPC flow (pick fit) |
| E3 | SSH hardening: PasswordAuthentication no – where? | sshd_config then sudo service sshd restart after test session |
| E4 | Why MD5 for passwords is wrong; name better | Rainbow / fast crack; use bcrypt/Argon2 |
| E5 | TLS: HTTP→HTTPS redirect checklist for Nginx | Listen 443 ssl; redirect 80; modern ciphers (defaults OK to start) |
| E6 | fail2ban: what does it ban and why Blue loves it | Repeated fails → jail IP; still need keys + SG |
| Red team (attacker) does | Blue team (defender) detects / stops |
|---|---|
| Uses stolen IAM key with AdminAccess | MFA; key age alerts; least privilege; GuardDuty-type findings |
| Brutes SSH; sprays passwords | Keys only; fail2ban; SG; monitoring /var/log/secure |
Ravindra Bagale's Tip
Students say "encryption" and "hashing" are the same. Interview: hash = one-way, for verification; encryption = two-way, to protect secrecy. Very simple – practise saying it out loud.
Ravindra Bagale's Tip – मराठी
Students "encryption" आणि "hashing" एकच म्हणतात. Interview: hash = one-way verify; encrypt = two-way, secrecy protect. एकदम simple – बोलून practice करा.
Ravindra Bagale's Tip – हिंदी
Students "encryption" और "hashing" को एक ही बताते हैं. Interview: hash = one-way verify; encrypt = two-way, secrecy protect. बिलकुल simple – बोलकर practice करो.
Lab
OWN Amazon Linux: enable key-only SSH in a new session before closing old one; install fail2ban (sudo yum install fail2ban where available) or document SG-only alternative; sudo service fail2ban start if installed. Notes: rollback plan.
Extended teaching notes
Why this lesson matters
Cryptography fails when people invent it. Use standard libraries, modern algorithms (AES-GCM, TLS 1.2+, bcrypt/argon2) and protect keys in a KMS or secrets manager.
Where crypto shows up
[('Passwords', 'bcrypt/argon2/PBKDF2 via the framework hasher — never plain MD5/SHA1.'), ('TLS', "Terminate on ALB/nginx with ACM/Let's Encrypt; redirect HTTP to HTTPS."), ('JWT / API tokens', 'Short lifetime, rotate signing keys, store secrets outside Git.'), ('Disk / S3', 'Provider or customer-managed keys; least privilege on decrypt.')]
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)
- Write the lesson title, date and the exact lab target you are allowed to use.
- List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
- Run one safe check from the lesson on a lab system only. Paste the command and output.
- Write a two-sentence fix you would give a teammate.
- 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.