Close the Mainframe Security Gap with Zero Trust

Sources: 1. IBM, 2. BMC, 3. IBM, 4. IBM

Why Zero Trust Is the Answer for Mainframe Security 

Zero Trust rests on a simple principle: never trust, always verify. Every user, every session, every access request must be authenticated and authorized – no matter where it originates. 

You've likely already applied Zero Trust to your cloud apps, web portals, and remote access tools. But the mainframe is often left out, still relying on static passwords and native access controls like RACF, ACF2, and Top Secret that bypass your enterprise identity systems entirely. 

That's the gap Zero Trust closes. Every login routes through your identity fabric, MFA is enforced before access is granted, sessions are monitored in real time, and every event is logged for audit – just like the rest of your enterprise. It's also a compliance enabler, helping you meet DORA, PCI DSS 4.0, NIST, and federal MFA mandates with audit-ready reporting. 

Zero Trust for the Mainframe: 7 Steps to Provable Security

1. Route all host access through a centralized security layer. 
Every session passes through a secure gateway that enforces corporate identity policies – no static passwords, no unmonitored green-screen sessions.

2. Enforce MFA and single sign-on for every user. 
On-premises or remote, users authenticate through the same identity provider – Microsoft Active Directory (AD), Microsoft Azure AD, Okta, or your platform of choice – via SAML or OIDC.

3. Monitor and log every session in real time. 
Centralized monitoring and audit logging give your team full visibility into mainframe activity and the evidence they need for audits and incident response.

4. Extend vulnerability management to the mainframe. 
Continuous scanning and configuration checks uncover critical vulnerabilities with over 99% accuracy – finding risks other tools miss.

5. Automate compliance and audit readiness. 
Automated reporting, patch auditing, and drift monitoring generate the evidence you need for DORA, PCI DSS 4.0, GDPR, and more.

6. Plan for rapid recovery and operational resilience. 
Surgical dataset recovery from a single point in time – within minutes – keeps your business running and your recovery objectives met.

7. Build security into your modernization roadmap. 
API-enabled connectivity, hybrid cloud integration, and identity federation extend your mainframe's capabilities while keeping your security posture strong.

Zero Trust Doesn't Stop at the Perimeter – and Neither Does Quantum Risk

Quantum computing may not pose an immediate operational threat to your mainframe today, but it presents a very real strategic risk to your data's confidentiality right now.

Here's why the clock is already ticking. Threat actors are using "Harvest Now, Decrypt Later" (HNDL) strategies – stealing encrypted data today so they can unlock it once functional quantum computers arrive. The data you protect this year could be exposed years from now, long after it left your control.

Mainframes are uniquely exposed to this threat for three reasons:

• Data gravity: Mainframes store decades of sensitive, regulated data – exactly the kind of high-value information attackers want to harvest.
• Longevity: Mainframe data often carries 20- to 40-year confidentiality requirements, meaning today's encrypted records must stay protected well into the quantum era.
• Crypto inertia: Many applications still rely on RSA key exchange, ECDSA signatures, and static keys embedded in legacy code – all vulnerable to quantum-enabled attacks.

The challenge isn't just the technology. It's visibility. Most organizations can't answer basic questions: Where is cryptography used? Which algorithms are in play? Which data is most exposed? Without those answers, quantum risk stays abstract – and abstract risk is impossible to manage or prove to a regulator.