45. Practice Exercises with Hints
45.5 Domains, S3, RDS and Project Checklist
DNS A/CNAME, HTTPS (Certbot), S3 Block Public Access, RDS not public, IAM role not long-lived keys – Part 6–8 revise.
| Exercise | Task | Hint |
|---|---|---|
| E1 | List DNS records needed for www + apex for a site on EIP |
A for apex (and/or www); CNAME www→apex common pattern – UI varies |
| E2 | S3: turn on Block Public Access; explain one risk if off | Accidental public object ACL / policy → data leak class |
| E3 | RDS: three checks before go-live | Not publicly accessible; SG from EC2 SG only; backups on |
| E4 | Project checklist: IAM role on EC2 vs access keys in PHP | Role + instance profile; no keys in code / git |
| E5 | Presigned URL idea in two lines (reels project) | Temporary access to private object; expiry matters |
| E6 | HTTPS: why HTTP login form is unacceptable | Credentials / cookies in clear on path – TLS required |
| Red team (attacker) does | Blue team (defender) detects / stops |
|---|---|
| Scrapes open S3 buckets / guesses object names | BPA; private ACLs; CloudTrail / access logs; least privilege |
| Connects to public RDS from internet | PubliclyAccessible false; SG lockdown; rotate creds if exposed |
Ravindra Bagale's Tip
Students say "the bucket is private" but an object ACL is public. Checklist: BPA + policy + object. Remember this.
Ravindra Bagale's Tip – मराठी
Students "bucket private आहे" म्हणतात पण object ACL public. Checklist: BPA + policy + object. लक्षात ठेवा.
Ravindra Bagale's Tip – हिंदी
Students कहते हैं "bucket private है" पर object ACL public है. Checklist: BPA + policy + object. याद रखो.
Lab
OWN account: create bucket sahyadri-lab-UNIQUE, enable BPA, upload a test object, confirm public URL fails. Delete bucket when done (empty first). Notes: 5 ticks checklist.
Real incident: Capital One (2019)
Public reporting described an attacker obtaining data from cloud storage after abusing a misconfigured WAF / SSRF-class path to reach instance metadata credentials, then listing and reading S3 data (as reported in court documents and major press). Weakness themes: SSRF to metadata + overly powerful role + broad bucket access. Defence for this drill: IMDSv2, least-privilege IAM, BPA, no unnecessary public. Source: US DOJ reporting and contemporaneous major coverage (verify; say "reported" for scale).
Extended teaching notes
Why this lesson matters
Use this lesson to strengthen systems you own: understand the risk, practise safely in a lab, then write and apply the fix.
Apply the fix across stacks
Same class of bug, same idea in every language.
Java / Spring Boot
Parameterise queries, encode output, CSRF tokens, limited Actuator, dependency scanning.
ASP.NET Core
EF Core / parameterised SQL, Razor encoding, HTTPS, Data Protection.
Node.js / Express
helmet, parameterised SQL, npm audit, avoid eval and shell concat.
Python / Django / Flask / FastAPI
ORM, autoescape, pip-audit, Bandit; never shell=True with user input.
PHP / Laravel
PDO/Eloquent, Blade escaping, composer audit.
Go / Ruby
database/sql placeholders / ActiveRecord; html/template / ERB escaping; govulncheck / Brakeman.
nginx / Apache / Tomcat
Hide versions, TLS, security headers, least-open ports.
MySQL / PostgreSQL / MongoDB / Redis
Private networks, auth on, least-privilege users, no 0.0.0.0/0.
AWS / Azure / GCP
Roles not long-lived keys, private data stores, cloud audit logs on.
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.