Common mistakes include treating vehicles as isolated systems, leaving diagnostic interfaces exposed, using weak update paths, and failing to segment safety-critical components from infotainment or telematics. Defenders should inventory ECUs and services, authenticate maintenance access, secure firmware updates, and monitor for abnormal in-vehicle and remote activity.
Why automotive security mistakes usually start with boundary assumptions
Most common failures come from assuming the vehicle is a closed, well-bounded system. Modern cars are software-heavy, externally reachable, and dependent on diagnostics, firmware, telematics, mobile apps, and back-end services. Once those boundaries are misunderstood, teams tend to underprotect the interfaces that actually move data, commands, and updates into the vehicle.
That is why the strongest first step is to map the vehicle as a connected system of ECUs, services, and trust relationships rather than a single embedded platform. NHIMG’s Automotive Cybersecurity Guide is the most direct place to anchor that model because it ties together vehicle architecture, CAN bus security, OTA updates, and related control points.
Another recurring mistake is to treat telematics, infotainment, and safety-critical functions as if they can fail independently without lateral impact. In practice, segmentation and trust boundaries matter because compromise in one zone can become a path into higher-consequence vehicle functions. Defenders need to think in terms of attack paths, not just component hardening.
Where diagnostic ports, firmware updates, and embedded trust usually go wrong
Exposed diagnostic interfaces are a classic weak point because they often exist for legitimate servicing but remain reachable longer than necessary or are not tightly authenticated. The same is true for update paths, which are frequently trusted too broadly, insufficiently integrity-protected, or operationally difficult to verify end to end. When these paths are weak, they become the easiest way to change behaviour at scale across a fleet.
Firmware and software update mistakes are especially damaging because they can turn a single control failure into a persistent compromise. A poor update design does not just affect availability, it can undermine trust in the software baseline, the rollback process, and any assumption that the current code state is known. That is why update authenticity, signing, and rollback safety are part of the security problem, not separate engineering details.
Even when the vehicle itself is well built, poor maintenance workflows can reopen the attack surface. Temporary service access, vendor tools, remote diagnostics, and workshop processes need the same discipline as production access because they often have deep authority. NHIMG’s Top 10 MFA Mistakes is useful here because it highlights a familiar failure pattern: weak recovery and exception handling often undo the protection that authentication was meant to provide.
How visibility and segmentation failures amplify automotive risk
The most consequential mistakes are usually the ones that let compromise spread quietly. If safety-critical ECUs are not segmented from infotainment or telematics, an attacker or faulty integration can move from low-risk functionality into high-impact control areas. If telemetry and in-vehicle activity are not monitored, that movement can persist without a clear signal until the behaviour is already operational.
Visibility gaps are particularly dangerous in vehicle environments because many events look like ordinary maintenance, connectivity, or user activity unless you already know the expected baseline. Inventory of ECUs, services, interfaces, and remote dependencies is therefore a security control, not just an asset-management exercise. Without that inventory, defenders struggle to prove what should be reachable, what should be updated, and what should be isolated.
For connected fleets, automotive security mistakes often resemble broader endpoint and OT failures, especially where operators expose too much trust to convenience, legacy support, or vendor access. NHIMG’s Top 10 OT Security Risks helps frame that shared problem of exposed interfaces, flat trust zones, and legacy dependencies, while Top 10 Endpoint Security Risks is a useful reminder that patching, tamper resistance, and monitoring failures often become the practical path to compromise.
Risk and Threat Considerations
Automotive security mistakes matter because the consequences are not limited to data loss. Weak boundaries, exposed diagnostics, and poor update trust can create remote attack paths into systems that affect safety, reliability, privacy, and fleet-wide integrity.
Failure mechanism: An attacker or rogue integration abuses a trusted maintenance, update, or in-vehicle interface, then uses weak segmentation or poor monitoring to reach additional ECUs or persist through future software changes.
Impact: The result can be unsafe vehicle behaviour, fleet-wide compromise, loss of integrity in deployed software, and a much harder incident response problem because the same trust paths used for servicing can also be used for abuse.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | IA-9 — Identification and Authentication (Non-Organizational Users) | Vehicle service and remote access paths depend on strong non-organizational authentication. |
| SC-7 — Boundary Protection | Vehicle segmentation and trust boundaries are central to limiting lateral movement. | |
| SI-2 — Flaw Remediation | Weak update paths and delayed remediation are core automotive security failure modes. | |
| Recommendation — Require strong authentication for vendor, workshop, and remote maintenance access. Enforce boundary controls that isolate infotainment, telematics, and safety-critical domains. Track and remediate firmware and software flaws through controlled update processes. | ||
| ISO/IEC 27001:2022 | A.8.9 — Configuration management | Vehicle configuration and ECU trust settings must be controlled to prevent exposure. |
| Recommendation — Manage ECU, interface, and update configurations through approved change control. | ||
| CIS Controls v8 | CIS-12 — Network Infrastructure Management | Segmentation and exposure reduction are central to connected vehicle security. |
| Recommendation — Segment vehicle networks and restrict unnecessary reachability between trust zones. | ||
Practitioner Guidance
What to verify: Confirm which interfaces are truly needed in production, which are only needed during maintenance, and which can be disabled, rate-limited, or isolated by environment. The critical question is not whether the interface exists, but whether it can still reach a high-consequence function after authentication and segmentation are applied.
Decision rule: If a path can alter vehicle state, receive firmware, or access diagnostic depth, treat it as privileged access and require stronger control than standard user connectivity. If the control cannot be independently validated in the field, assume the operational process is part of the risk and tighten the workflow before scaling it.
What practitioners underestimate: The hardest problems are often trust reuse and exception creep, not a single obvious vulnerability. A vehicle program can look secure on paper while workshop access, update tooling, remote support, or telematics exceptions quietly recreate the same exposure across many units.
Practitioner takeaway: Automotive security is won by controlling trust boundaries, not by hardening one subsystem at a time; if the servicing path can change software or reach safety-critical functions, it must be treated as production-grade privileged access.
Related resources from NHI Mgmt Group
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- What are the common mistakes organisations make when setting up third-party security testing?
- What are the most common mistakes teams make when answering security questionnaires at scale?
- What are the common implementation mistakes when connecting alert feeds to security operations?