Written & verified by:
Sab Esati – Smart Lock & Cyber Security Specialist
Accredited by RMIT University and Chisholm Institute
As smart locks become more common in homes and small businesses, the discussion around security is shifting. The question is no longer just “Are smart locks safe?” it’s “What risks do they introduce, and how are those risks managed?”
In cyber security, one of the most effective ways to evaluate any system is through threat modelling. Instead of assuming something is secure or insecure, we break it down into four simple areas:
- What are we protecting?
- Who might try to attack it?
- Where could vulnerabilities exist?
- How are those risks mitigated?
When applied to smart locks, this approach gives a clearer and more realistic view of how secure they are.
Defining the Assets
At the core, a smart lock protects one primary asset: controlled access to a physical space.
Supporting that are other assets:
- Digital credentials (PIN codes, biometrics, app access)
- User accounts linked to the lock
- Unlock history and activity logs
- Optional gateway and network connectivity
Everything revolves around managing who can enter and how that access is controlled.
Physical vs Digital Attack Surface
Traditional locks are almost entirely physical. The risks are familiar:
- Lock picking
- Forced entry
- Key duplication
- Hidden spare keys
Smart locks still rely on mechanical components like mortises and deadbolts, but they also introduce a digital layer. That digital layer changes the attack surface it doesn’t automatically weaken it.
Digital Entry Points Can Include:
- Bluetooth communication
- Keypad input
- App authentication
- Optional Wi-Fi gateway access
From a security perspective, adding digital controls introduces new considerations — but also new protections.
Identifying Realistic Threat Actors
In residential environments, most threats are not highly sophisticated hackers. They’re typically:
- Opportunistic criminals
- Former guests or contractors with lingering access
- Someone who finds or steals an unlocked phone
Understanding realistic threat actors is important. Most attacks in home environments are opportunistic, not advanced cyber operations.
Evaluating Key Vulnerabilities
Bluetooth Attack Vectors
Most smart locks use encrypted Bluetooth for local control. Bluetooth limits exposure because:
- It requires close physical proximity
- It is not internet-facing by default
Unlike always-online devices, this reduces remote attack opportunities. While theoretical risks like signal interception exist, encrypted communication and authenticated sessions make exploitation extremely difficult in real-world residential settings.
Brute Force on PIN Codes
Any keypad system introduces the possibility of repeated guessing attempts.
Mitigation typically includes:
- Temporary lockouts after failed attempts
- Tamper alerts
- Logged failed entries
This mirrors account lockout policies used in enterprise systems. It’s a controlled and monitored environment, not unlimited guessing.
Replay Attacks
A replay attack involves capturing a valid communication signal and attempting to reuse it.
Modern encrypted communication prevents this by using dynamic session authentication rather than static commands. Without authenticated sessions, replay attempts fail.
Insider Threats
One of the most underestimated risks isn’t technical it’s behavioural.
Examples include:
- Sharing permanent PIN codes too widely
- Forgetting to revoke access after work is completed
- Using predictable codes
This is known as an insider threat. The advantage smart locks offer here is visibility and control. Access can be:
- Temporary
- Recurring
- Instantly revoked
Traditional keys offer none of that. If a key is copied, you may never know.
Gateway & Network Exposure
When paired with a Wi-Fi gateway for remote access, the attack surface expands to include the home network.
However, this risk is manageable through:
- Strong router passwords
- WPA2 or WPA3 encryption
- Updated firmware
- Avoiding unnecessary port forwarding
Importantly, remote access is optional. Local Bluetooth operation remains separate, meaning internet exposure is not mandatory.
Mitigation Through Layered Security
Well-designed smart lock systems rely on layered protection:
- Encrypted communication
- Authenticated accounts
- Controlled credential management
- Activity logging
- Strong mechanical components
Security is not about eliminating all risk it’s about managing it intelligently.
From a cyber security perspective, the greater risks in most residential setups are not advanced technical exploits. They are:
- Weak passwords
- Poor phone security
- Oversharing credentials
- Misconfigured home networks
Technology can be secure, but user behaviour still matters.
Final Assessment
When viewed through a threat modelling lens, smart locks do not remove risk entirely no system does. What they do is shift risk from purely physical vulnerabilities to a more controlled, monitored, and revocable access model. They introduce digital considerations, but they also introduce stronger access control, visibility, and accountability.
Security isn’t about fear. It’s about understanding the system, identifying realistic risks, and deploying it properly. When implemented with basic security hygiene and responsible access management, smart locks represent a well-mitigated IoT entry system not a vulnerability.