Your organization spent six figures on security last year. MFA is enforced. Conditional Access policies are active. The Microsoft Secure Score looks strong. By every visible metric, you've built a defensible security posture.
Then ask one question: How many personal devices accessed your Microsoft 365 environment this week without any corporate security controls?
If the answer is "we don't know," you've found the blind spot. And attackers found it before you did.
This is Zero Trust's most common failure mode. Organizations invest in identity verification and access controls while leaving the device layer unmanaged. The result: a security architecture that verifies who is logging in but trusts whatever they're logging in from.
46% of systems found in credential breach logs are unmanaged devices. For financial institutions holding borrower records, member account data, and wire transfer approvals, that blind spot doesn't just represent a technical gap. It represents regulatory exposure, insurance risk, and reputational liability.
Zero Trust is built on a simple principle: verify everything, trust nothing. In practice, most implementations verify two of three pillars and skip the third.
Pillar 1: Identity. Who is requesting access? This is where most organizations invest first. MFA deployment, phishing-resistant authentication, Entra ID risk-based sign-in policies. Most financial institutions handle this well.
Pillar 2: Access. What should this identity be allowed to do? Conditional Access policies, role-based permissions, geographic restrictions. Increasingly mature at regulated institutions.
Pillar 3: Device. Can we trust what they're accessing from? This is where the blind spot lives. A verified user with valid permissions connecting from a compromised personal laptop is still a breach waiting to happen. Most Zero Trust deployments either skip this pillar or apply it inconsistently, managing corporate laptops but excluding personal phones, tablets, and home computers.
CISA's Zero Trust Maturity Model is explicit: all devices accessing organizational resources must be secured under Zero Trust principles, whether enterprise-owned or BYOD. If your implementation manages corporate endpoints but ignores personal devices, you've built two-thirds of a security architecture. The missing third is the one attackers exploit.
Financial services operates under a regulatory framework that specifically requires controls over how sensitive data is accessed. The blind spot isn't just a security gap. It's a compliance gap.
Examiner expectations are specific. FFIEC, NCUA, and state regulators ask how institutions manage endpoint security. "We have MFA" answers the identity question but not the device question. An NCUA examiner finding that personal phones access member data without any management controls will flag it. An FFIEC auditor seeing no device compliance policies will note the gap.
Cyber insurance is tightening. Carriers are adding device management questions to their underwriting process. Can you enforce encryption on endpoints? Do you have remote wipe capability? Can you block non-compliant devices? Gaps here mean higher premiums or coverage exclusions. When a breach occurs through an unmanaged device, insurers have grounds to challenge the claim.
The data exposure is concentrated. A personal phone that accesses your Microsoft 365 environment doesn't just reach email. Through Single Sign-On, it reaches Teams, OneDrive, SharePoint, and potentially your loan origination system, core banking platform, or board documents. One unmanaged device accesses the same data an attacker would target.
The scale of unmanaged device exposure across financial services:
The behavioral reality compounds the technical risk. A loan officer who would scrutinize a suspicious email on a corporate laptop will tap a text link on a personal phone without hesitation. Mobile phishing attacks reach users through SMS, messaging apps, and social media where enterprise email filters don't operate.
The solution isn't banning personal devices. That's impractical in a sector where loan officers, branch staff, and executives need mobile access to remain productive. The solution is extending Zero Trust to include device-level verification without creating organizational resistance.
Mobile Application Management through Microsoft Intune secures corporate data inside approved apps without managing the entire device. Deploy app protection policies on Outlook, Teams, and OneDrive that require PIN or biometric access, encrypt business data at rest, block data transfer to personal apps, and enable selective wipe of corporate data only.
MAM deploys in weeks and addresses the most urgent exposure. The message to employees: your personal phone stays personal. We're protecting company data inside the apps you use for work.
After MAM builds trust and demonstrates the approach, expand to device enrollment through MDM. This gives your security operations the ability to verify device encryption, enforce OS patch levels, detect jailbroken devices, and deploy mobile threat defense. Roll out in waves, starting with higher-risk roles and expanding quarterly.
Connect both MAM and MDM to Conditional Access policies. Devices that don't meet compliance standards get blocked from accessing sensitive resources. Devices that are enrolled and compliant get seamless access. The compliant path becomes the easiest path, which drives adoption faster than any mandate.
For detailed guidance on the Conditional Access rules that make this work, see our article on 5 Conditional Access rules every financial institution needs. For the Intune compliance policies that feed these rules, see our guide on risk-based device compliance with Microsoft Intune.
Organizations that close the device blind spot see measurable results:
The ROI isn't theoretical. It's the difference between a partial security architecture that looks good on dashboards and a complete architecture that actually stops attacks.
ABT has deployed Zero Trust device security across 750+ financial institutions. We've seen the pattern repeatedly: strong identity controls paired with weak or absent device management. Guardian is built to close that gap.
Guardian's device security lifecycle:
As a Tier-1 Microsoft CSP, ABT provides the same Microsoft licensing you'd get buying direct. Guardian adds the security configuration, compliance alignment, and ongoing management that turns licensed tools into actual protection.
Talk to an ABT expert about closing your Zero Trust blind spot or run a free Security Grade Assessment to find out what your current security posture doesn't measure.
The most common blind spot is unmanaged personal devices. Most organizations invest in identity verification through MFA and access controls through Conditional Access but skip the device trust pillar. This means verified users can access sensitive data from compromised, unpatched, or jailbroken personal devices without any corporate security controls applied.
Secure Score measures whether recommended security controls are enabled in your Microsoft 365 tenant. It rewards policy enablement but has no visibility into personal devices accessing corporate resources outside management controls. An organization can score above 85% while dozens of unmanaged phones and tablets access borrower or member data daily.
FFIEC, NCUA, and state regulators require demonstrable controls over how sensitive financial data is accessed. Device management provides the evidence that endpoints accessing borrower and member information meet encryption, patch level, and security baselines. Without device compliance documentation, institutions face examination findings and potential enforcement actions.
Yes. The MAM-first approach secures corporate data inside approved applications on personal devices without managing the phone itself. Employees keep full control of personal content while business data stays encrypted, contained, and remotely wipeable. MDM enrollment can follow later for organizations that need deeper device-level compliance verification.
Organizations that complete the device pillar of Zero Trust report 21% better visibility into critical systems, 50% fewer security incidents compared to partial implementations, and 38% lower breach costs. For financial institutions, the additional benefit is documented compliance evidence that satisfies NCUA, FFIEC, and state examiner expectations during audits.