43. IoT and OT Security – Cameras, Smart Devices, Plant Networks

43.4 Mirai-Class Botnets – Weak IoT, Outbound C2

By Ravindra Bagale Last updated: 15 October 2026

Mirai (2016, public reporting): malware that guessed default / weak credentials on internet-facing IoT (cameras, routers, DVRs), then used the army for DDoS. October 2016 attacks on DNS provider Dyn caused wide service disruption for many sites; Dyn and partners reported Mirai-related traffic from a very large set of IPs (tens of millions of discrete addresses observed in the attack traffic, as Dyn stated – verify). Later U.S. cases involved people who created/shared Mirai code (public court reporting).

SME / ISP lessons for Blue:

Your camera becomes someone else's cannon – outbound floods, not only inbound viewing
ISP may cut your line; reputation of your public IP burns
Fix = unique passwords, no WAN management, firmware updates, egress allow-lists for IoT VLAN

Red team (attacker) does	Blue team (defender) detects / stops
Brute default Telnet/SSH on exposed IoT	No WAN Telnet; unique creds; vendor blocklists
Points botnet at a victim (DDoS)	Egress rate caps on IoT VLAN; detect odd outbound
Shares Mirai-class builders	Never download; IR + legal path if you find infection

Ravindra Bagale's Tip

Students call downloading the Mirai source from GitHub "research". That is not in our book. Interview: "I harden IoT so it cannot join a botnet; I do not run botnet code." Remember this.

Lab

Design-only: draw Sahyadri IoT VLAN – cameras → firewall → internet. Mark blocked outbound except NTP + vendor update HTTPS. 6 sentences on why "cameras need full internet" is usually false.

Real incident: Mirai and the Dyn DNS disruption (2016)

On 21 October 2016, Dyn's managed DNS infrastructure faced large, multi-wave DDoS events that disrupted access to many popular services for users in North America and Europe (widely reported). Dyn stated that analysis with partners (including Flashpoint and Akamai) confirmed Mirai-infected devices as a significant source, with attack traffic associated with tens of millions of IP addresses. Root weakness on the IoT side: devices with default or trivial credentials reachable from the internet. Defence for SMEs: change defaults, disable remote admin, patch, keep cameras off the open internet, watch egress. Source: Dyn public statements on the 21 Oct 2016 attack; major contemporaneous reporting (verify; say "reported" for scale).

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)

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.