In financial services, security is not judged by what you say you have. It is judged by what you can show. That is why ISO 27001 and the Essential Eight are being asked about more often. They give leaders, auditors, and insurers something solid to measure.
But they are not the same kind of standard. ISO 27001 is a structured way to run information security as a system, with scope, governance, and auditability. The Essential Eight is a prioritised set of controls that lives or dies on consistency and coverage.
If you are deciding what “good” looks like for your organisation, this is the practical comparison. What each framework is for, what it asks of you, and how to approach it without building a program that looks fine on paper and fails in day-to-day operations.
If you want a practical way to stress-test providers before you commit, A Comprehensive Guide to Choosing the Right Cyber Security Services Partner is a good next read.
Understanding ISO 27001
ISO/IEC 27001 is an international standard for running an Information Security Management System (ISMS). In plain terms, it is how you run information security with clear scope, ownership, and evidence.
In practice, ISO 27001 is about setting up a system that answers a few hard questions:
- What is in scope, and what is not
- Who owns security decisions and control operation
- How security risks are assessed and treated
- What controls apply, recorded in the Statement of Applicability (SoA)
- How you review performance and fix what is not working
ISO 27001 is not a one-off project. It only matters if the system is operated, checked, and maintained.
Understanding the Essential Eight
The ASD Essential Eight is a prioritised set of mitigation strategies. It is widely used in Australia because it focuses on controls that disrupt common attacker techniques.
The eight strategies are:
- Application control
- Patch applications
- Configure Microsoft Office macro settings
- User application hardening
- Restrict administrative privileges
- Patch operating systems
- Multi-factor authentication
- Regular backups
The maturity model matters because it forces consistency. It is the difference between having a control written down and having a control you can rely on day-to-day.
Comparison: ISO 27001 vs Essential Eight
Scope and Intent
ISO 27001 and the Essential Eight solve different problems.
ISO 27001 is about running information security as a managed system. Scope, accountability, internal checks, and evidence.
Essential Eight is a technical mitigation baseline focused on consistent operation of key controls, measured through maturity levels.
Put simply:
- Essential Eight answers: “How strong and consistent are your core IT security controls?”
- ISO 27001 answers: “Do you run security as a system you can scope, govern, check, and prove?”
Overlap
They overlap, but they are not interchangeable.
- Essential Eight can be your practical baseline for core technical controls.
- ISO 27001 is how you define what is in scope, assign ownership, document what controls apply, and keep evidence that the controls are operating.
The DEWR Right Fit for Risk sets out what a properly scoped ISMS should demonstrate, including documenting control applicability through the Statement of Applicability.
Decision Logic for Financial Services
Choosing between ISO 27001 and the Essential Eight is less about labels and more about what you need to prove, and how quickly you need to prove it.
-
Need fast, measurable control uplift
Lead with the Essential Eight maturity model. This suits teams that need immediate improvement in control consistency and proof that the basics are being run properly. -
Need a formally scoped, auditable security management structure
Lead with ISO 27001 alignment. This suits organisations that need a clear scope, defined ownership, and an evidence trail that holds up in assurance reviews. If certification is on the table, it is usually driven by customer requirements, supplier assurance, or internal governance expectations. -
Need both outcomes
Set scope and ownership using ISO 27001, then lift control maturity using the Essential Eight inside that scope. This avoids the common failure mode where controls exist, but nobody can show who owns them, how exceptions are handled, or what evidence exists.
Before you move into the practical pathway, lock three decisions:
- What outcome you need to prove: control maturity, auditability, or both
- What is in scope: systems, identities, suppliers, and data that matter
- What evidence you will rely on: reports, test results, reviews, and documented decisions
Make those calls early, and the pathway work becomes disciplined, faster to evidence, and easier to sustain.
Practical Pathway: How to Choose and Sequence It
Start by being clear on what you are being asked to prove.
For APRA-regulated entities, CPS 234 is a non-negotiable reference point for expectations around security capability, controls, and incident management.
If you need to connect technical work to board expectations, policy, and audit-ready structure, Governance, Risk and Compliance is a solid starting point.
Then choose your lead approach:
- Lead with Essential Eight when the priority is fast, measurable uplift in core controls and consistent operation.
- Lead with ISO 27001 when you need a formally scoped security management system with clear ownership, review cadence, and evidence that stands up to scrutiny.
- Do both when you need the control uplift and the assurance structure. Use ISO 27001 to set scope and accountability, then use Essential Eight to drive control consistency and proof.
Operationally, keep the focus on what holds up in real scrutiny: restore tests that prove backups work, patch reporting with exceptions tracked, privileged access reviews with outcomes recorded, and monitoring that shows triage and escalation.
If you want the same secure-by-design discipline applied to the day-to-day environment that these controls depend on, Managed IT Services is where that operating model is set out.
Take the Clear Path Forward
If you’re in financial services, the goal is to build a security posture you can explain, evidence, and sustain.
SIAX helps you turn Essential Eight maturity and ISO 27001 alignment into practical work that stands up to board scrutiny, audits, and assurance reviews.
If you want a clean starting point, we’ll map your current state, confirm what outcomes you need to prove, and set a target your team can maintain. Then we build the evidence pack and the operational capability to keep it running.
Our Cyber Security Services page maps out how SIAX approaches uplift and operational security.
Frequently Asked Questions
What is ISO 27001 and who is it for?
ISO/IEC 27001 is an international standard for running an Information Security Management System (ISMS). It suits financial services organisations that need clear scope, ownership, and evidence.
What does ISO 27001 compliance involve?
ISO 27001 compliance means operating an ISMS to the standard within a defined scope. It includes governance, internal reviews, and evidence, including a Statement of Applicability (SoA).
How does the Essential Eight improve security maturity?
The Essential Eight is a prioritised set of mitigations built around consistent operation. The Essential Eight maturity model focuses on coverage and proof, not just tools.
ISO 27001 vs Essential Eight, which should a financial services firm choose?
Need fast, measurable control uplift: lead with the Essential Eight. Need an auditable management system: lead with ISO 27001. Many use both, ISO 27001 for scope and governance, and the Essential Eight for control consistency.
How do managed security services support ISO 27001 and Essential Eight outcomes?
They help run controls consistently and produce evidence. That includes monitoring and response, identity hardening, patch and vulnerability governance, restore testing, and reporting that supports assurance and CPS 234 expectations where relevant.