Home IoT Risk Game: Spend Your Defenses Wisely

A threat model becomes useful when you have to make choices.

Real homes do not have unlimited money, unlimited time, or a security engineer assigned to every light bulb. The Garden State Cyber curriculum uses a home-IoT game and threat-model worksheet to force that trade-off.

This lab does the same thing with a fictional smart home.

You will not scan, connect to, or test any real household device.

The fictional home

The Rivera family has these connected systems:

• home router
• two laptops
• smart speaker
• video doorbell
• baby monitor
• smart thermostat
• streaming television
• two phones

The devices use a mixture of local Wi-Fi and vendor cloud services.

Your job is to reduce the largest risks with a limited defense budget.

Step 1: map the system

Draw the home as a simple network and service diagram.

Include:

• internet connection
• router
• higher-value personal devices
• IoT devices
• cloud services
• phones used to control devices

Mark trust boundaries between:

• home and internet
• user accounts and vendor cloud
• higher-trust computers and lower-trust IoT devices
• physical devices and mobile apps

Step 2: draw threat cards

Use these six synthetic threat cards.

Card A: reused account password

The smart-camera account uses the same password as another service.

Card B: unsupported device

The baby monitor vendor stopped providing updates two years ago.

Card C: broad network trust

Every IoT device shares the same local network as the family's laptops.

Card D: exposed data

The doorbell stores video in a cloud account with no MFA.

Card E: default settings

The router still uses an old default administrator password.

Card F: cloud outage

The thermostat loses remote-control features when the vendor cloud is unavailable.

For each card, identify:

• asset
• threat or failure
• weakness
• CIA impact
• likelihood
• impact
• confidence

Step 3: spend 10 defense points

You have 10 defense points.

Each control costs points:

Spend no more than 10 points.

You are allowed to leave risks unresolved.

That is the point.

Step 4: defend your priorities

For every control you buy, explain:

• which threat card it addresses
• why it outranks another possible control
• what risk remains after the change

Then identify the highest residual risk you could not afford to solve.

A strong answer may decide that replacing an unsupported baby monitor is more important than improving a low-value convenience device.

Another group may rank network separation first.

Both can be defensible if the assumptions are explicit.

Step 5: change one assumption

The teacher reveals one new condition:

Choose or draw one:

• a family member works from home with sensitive files
• the baby monitor is no longer used
• the router cannot create a separate IoT network
• the camera account already has MFA
• the thermostat controls a critical medical-storage room instead of a normal home room

Recalculate your priorities.

What changes?

Threat modeling is valuable because priorities should respond to context.

Step 6: build "My IoT Threat Model"

Create a final worksheet for one fictional IoT device.

Include:

Device purpose

What does it do?

Assets

What data, access, or function matters?

Data flow

Where does information travel?

Trust boundaries

Where does control cross between user, network, device, and cloud?

Top three threats

Describe the failure, not just the attacker.

Controls

Choose a practical control for each threat.

Residual risk

What remains after the controls?

End-of-support question

What should happen when the vendor stops updating the device?

Do not confuse smart with secure

A device can have impressive features and weak security support.

Before buying or deploying a connected device, ask:

• Will it receive updates?
• Can credentials be changed?
• Is MFA available?
• What data leaves the home?
• What happens if the cloud service disappears?
• Can the device be isolated or removed cleanly?

Security is part of the product lifecycle.

Evidence for Lesson 3

Submit:

• complete fictional home diagram
• six threat-card ratings
• 10-point defense budget
• revised budget after the changed assumption
• My IoT Threat Model worksheet

Finish with:

The control I spent the most resources on was ________ because the risk combined ________ with ________.

A threat model is not a list of everything frightening. It is a record of what you chose to care about first, why, and what risk you knowingly left behind.