ISO 27001 internal audit

February 14, 2026

If your business handles sensitive data, an ISO 27001 internal audit is often the first real test of your security setup. It checks if your Information Security Management System, or ISMS, actually works as planned. Many Australian organisations run one before booking an external certification audit to avoid nasty surprises.

I’ve done hundreds of these over 20 years in cybersecurity. Most businesses find gaps they did not expect, but fixing them early saves time and money. Let’s walk through what an ISO 27001 internal audit really means for you.

What exactly is an ISO 27001 internal audit?

ISO 27001 sets out requirements for an ISMS. The standard covers everything from risk assessments to access controls and incident response. An internal audit tests whether your organisation meets those requirements.

You do it yourself or bring in experts like us at Siege Cyber. The goal is simple: gather evidence that your controls operate effectively. Auditors look at documents, interview staff, and check systems hands-on.

Under clause 9.2 of the standard, you must plan these audits at planned intervals. That means yearly at least, or more if risks change. For Australian firms under the Privacy Act or APRA CPS 234, this aligns with your legal duties too.

Why bother with an ISMS internal audit?

Businesses skip internal audits at their peril. Certification bodies like BSI or JAS-ANZ demand proof of them before they sign off. Without one, you risk failing your stage 1 or stage 2 audit.

It also spots weaknesses early. Say your risk treatment plan looks good on paper, but staff bypass controls daily. An internal audit catches that. We have seen organisations shave months off certification timelines by acting on our findings.

Plus, it builds internal know-how. Your team learns the standard inside out, making ongoing compliance easier. In Australia, with ASD’s Essential Eight in play, tying your ISMS audit to those maturity levels gives regulators confidence.

Steps in an ISO 27001 internal audit

Internal audits follow a clear process. Start with a plan based on your Statement of Applicability, which lists your chosen controls from Annex A.

Scope the audit: Pick high-risk areas like cloud access or supplier management.
Develop a checklist: Use the standard’s clauses and your risks.
Gather evidence: Review policies, logs, and training records.
Conduct fieldwork: Talk to people, test controls, sample data.
Report findings: Note conformities, non-conformities, and opportunities for improvement.
Follow up: Track fixes until resolved.

Common gaps we find in ISO 27001 gap analysis

Most organisations come to us for an ISO 27001 gap analysis first. It is like a lighter version of the full internal audit, rating your ISMS against the standard.

Top issues include:

Incomplete risk assessments that miss insider threats.
Access controls where privileged accounts lack multi-factor authentication.
Incident response plans never tested in a real drill.
Supplier risks not documented, especially for offshore vendors.

One client in Sydney had solid policies but no monitoring logs. Their gap analysis showed 40% of controls needed work. Six months later, they passed certification. [INTERNAL LINK: ISO 27001 gap analysis – link to /services/iso-27001-gap-analysis]

If you are not sure where your organisation stands, book a gap analysis with Siege Cyber. It is a low-risk way to benchmark progress.

Outsourced ISO 27001 audit: When to bring in consultants

Some teams try DIY audits. Fine if you have spare compliance staff. But most businesses lack the time or expertise.

That is where ISO 27001 consultants Australia come in. Outsourcing keeps things objective. Your internal team might overlook familiar bad habits, but fresh eyes spot them fast.

At Siege Cyber in Brisbane, we do outsourced ISO 27001 audits tailored for Australian rules. We factor in the Notifiable Data Breaches scheme and Essential Eight. Our reports map straight to certification needs.

We have helped finance firms hit APRA CPS 234 and health providers meet Privacy Act demands. No fluff, just practical fixes.

ISO 27001 compliance Australia: Making it stick

Compliance is not a one-off. Post-audit, management review clause 9.3 pulls it all together. Review audit results, risks, and performance metrics.

Then maintain it. Regular internal audits keep your ISMS alive. Tie them to business changes like new cloud setups or mergers.

For ISO 27001 Australia certification, expect surveillance audits yearly and recertification every three years. Stay ahead by auditing twice a year.

How Siege Cyber makes your internal audit painless

We have run internal audits for dozens of Australian organisations. From startups to ASX-listed firms, we cut through the noise.

Our process:

Free initial chat to scope your needs.
Fixed-price audit with clear timelines.
Actionable report with prioritised fixes.
Handover to your team or full implementation support.

As partners with Vanta and Drata, we integrate automation where it shines, like evidence collection. But we provide the human judgement platforms cannot, like nuanced risk calls.

Siege Cyber has been helping businesses across Australia with penetration testing, compliance, and cyber risk for over 20 years. If you’d like to discuss what type of testing makes sense for your organisation, or if you’re preparing for an ISO 27001 or SOC 2 audit and need testing as part of that process, get in touch.

You can reach us at siegecyber.com.au or email [email protected] directly. We’re based in Brisbane but work with clients across the country.