Ravindra BagaleCourses & study guides मराठी Track your progress

40. DoS and DDoS – Availability Attacks

40.6 Botnets and IoT – Mirai-Class Lesson

By Last updated:

Botnet = many compromised devices obeying C2. Mirai-class public history: IoT cameras/DVRs with default passwords recruited into DDoS armies; source code release made copycats easy (public reporting).

Blue for Maharashtra SMB + home lab students:

  • Change default IoT passwords; isolate cameras on guest VLAN
  • Patch firmware when vendor ships fixes
  • Egress filter: IoT subnet should not open random outbound to weird C2 ports
  • Don't expose admin UIs to the internet
Red team (attacker) does Blue team (defender) detects / stops
Scans for IoT defaults; enrolls bots Unique passwords; network segmentation; disable UPnP where unsafe
Uses botnet for hire (crimeware market – awareness only) ISP/cloud scrubbing; never "rent bots" yourself (illegal)
Targets DNS providers / single big VIP Multi-DNS; Anycast; capacity partners

Ravindra Bagale's Tip

Students leave the home CCTV on admin/admin and bridge it to the office VPN. IoT = DDoS fuel + a pivot into the office. Use a guest VLAN + a strong password. Interview: the Mirai lesson = defaults + exposure, not "I built a botnet."

Practice task

Amir (fictional IT, Solapur) la 12 IoT cams. Write 8-step hardening runbook: password, firmware, VLAN, firewall egress, inventory spreadsheet for owner Raja. No scanning the public internet for cameras.

Real incident: Krebs on Security / Mirai era (2016)

Public reporting described a very large DDoS against Krebs on Security in September 2016, with telemetry discussed in the hundreds of Gbps range and later Mirai analysis by Cloudflare and others. Akamai's free protection for the site was withdrawn under the load (reported), forcing a hosting change. Lesson: even strong CDN relationships have limits; IoT defaults powered much of Mirai. Source: Krebs on Security posts / Cloudflare Mirai retrospective (verify; say "reported" for sizes).

Extended teaching notes

Why this lesson matters

Availability attacks try to exhaust bandwidth, connections or app workers. Learning them is about detection and defence — never about stressing networks you do not own (that can be illegal and harmful).

  • Rate limits and WAF/CDN at the edge.
  • SYN cookies / tuning on servers.
  • Autoscaling with care (cost controls).
  • Keep IoT devices off default passwords (Mirai lesson).
  • Lab simulations only on isolated networks you own.

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.