What are common mistakes in building automation security?

Where building automation security mistakes usually start

Most failures come from treating building management systems as office IT instead of operational technology with long-lived equipment, vendor dependencies, and physical consequences. Flat networks, permissive remote access, and weak credential hygiene create the easiest path for both opportunistic scanning and targeted abuse. For an overview of the system boundary and common exposure points, see the Building Management System Security Guide.

The practical mistake is assuming that a working BAS is a secure BAS. In reality, security problems often sit in architecture choices, such as shared management planes, weak segmentation between engineering and safety-relevant controls, and remote support paths that were added for convenience and never tightened. Those conditions matter because they let a small compromise spread into HVAC, access control, lighting, alarms, or other integrated building functions.

Remote access deserves special scrutiny because it is often the first externally reachable trust boundary. Exposing vendor portals, jump hosts, or maintenance channels without strong authentication, session control, and logging makes it far easier for an attacker to reach management interfaces and change schedules, setpoints, or controller logic without immediate detection. A useful lens on that pattern is the Top 10 OT Security Risks.

Why configuration and access hygiene fail in practice

Default credentials, reused vendor passwords, and shared accounts remain common because they are easy during commissioning and painful to unwind later. The result is weak accountability, broad blast radius, and little confidence that an unexpected change came from an approved operator rather than a compromised credential or an overbroad support account.

Patching is another recurring failure point. Building environments often run long-lived controllers, gateways, and supervisory servers that are left unpatched because of uptime concerns, compatibility worries, or unclear ownership between facilities, IT, and integrators. The mistake is not just missing updates, but failing to maintain an inventory and an exception process that tells you what is exposed, what is compensating for unpatched devices, and what still needs vendor support.

Another common miss is access scope. Third-party maintenance should be tightly bounded, reviewed, and removed when no longer required. If vendors can reach too much of the environment for too long, a routine support relationship becomes a standing access path that is hard to distinguish from misuse.

What monitoring and recovery teams often overlook

Many building teams watch only for outages, not for malicious or unsafe-but-plausible changes. That leaves blind spots around setpoint drift, schedule changes, controller overrides, and unusual remote logins. A good control story depends on logging that is actually reviewed, not merely enabled, and on alerts that distinguish operational changes from normal maintenance windows.

Backup and recovery are also often under-tested. It is not enough to know that backups exist; teams need to know whether controller configurations, historical schedules, and recovery images can be restored quickly enough to limit business disruption. If recovery depends on the same credentials, same network path, or same vendor account as daily administration, the backup path can fail for the same reason the primary path failed.

For teams formalising automation and response around these environments, the SOAR and Security Automation Guide is useful for thinking about where automation helps and where human approval is still needed. It is also worth comparing the control pattern with the Top 10 Secrets Management Mistakes, because many building environments fail in the same way when shared passwords, hardcoded credentials, and weak rotation are left in place.

Risk and Threat Considerations

Building automation mistakes are risky because they can move from an IT hygiene issue to a physical operations issue very quickly. The same weak remote access or flat network that exposes a server can also expose environmental controls, occupant comfort, access systems, or safety-related devices, creating a larger operational and reputational impact than teams expect.

Failure mechanism: Attackers or unauthorized users exploit weak segmentation, default credentials, or exposed remote access to reach management interfaces, then alter schedules, setpoints, or controller logic while blending into routine operational traffic.

Impact: The outcome can include service disruption, energy waste, tenant complaints, loss of environmental control, and in some environments a wider safety or business continuity incident.

Practitioner Guidance

What to prioritise: Start with the trust boundaries that can change the building’s behaviour, not just the servers that administer it. Segment management networks, remove direct exposure where possible, and treat vendor access as a privileged exception that must be time-bound and auditable.

What to verify: Confirm that every remote path uses strong authentication, that default or shared credentials have been removed, and that logs capture who changed what, when, and from where. Then test a recovery path, because a backup that cannot restore controller state or schedules is not a real control.

Practitioner takeaway: building automation security usually fails where convenience became permanent, so the right question is not whether the system works, but whether every access path, change path, and recovery path is still justified, isolated, and observable.

Related resources from NHI Mgmt Group

• What are common mistakes with Smart Building Security?
• How should security teams prioritise NHI remediation in cloud environments?
• How should security teams govern non-human identities at scale?
• How should security teams govern non-human identities for compliance?