Business Mobile Security: Protecting Company Data on Phones

What Is Business Mobile Security?

Business mobile security refers to the full set of technical controls, policies, and software that protect company data on smartphones and tablets. As part of a broader business mobiles strategy, mobile security ensures that every device accessing corporate email, files, and applications meets a defined security baseline — whether the device is company-owned or a personal handset used under a BYOD arrangement.

A modern company phone is a powerful computing device. It holds email, contacts, sensitive files, access to cloud applications such as Microsoft 365, and often multi-factor authentication (MFA) codes. Without appropriate controls, a lost or stolen phone is effectively an unlocked door into your entire business. Mobile malware attacks increased 50% year-on-year (industry sources), and 43% of UK businesses experienced a cybersecurity breach in 2025 (DSIT Cyber Security Breaches Survey). These figures make it clear that mobile security is no longer optional — it is a fundamental part of any organisation's defence posture.

The National Cyber Security Centre (NCSC) recommends that all businesses implement mobile device management and enforce a minimum security baseline on every device that accesses company data. This applies equally to company-owned handsets and personal devices used for work.

How Business Mobile Security Works in Practice

Mobile security is typically enforced through Mobile Device Management (MDM) software. Microsoft Intune, included in Microsoft 365 Business Premium, is the most widely adopted platform among UK SMEs. When a device is enrolled in Intune, the administrator can push security policies — mandatory PIN or biometric lock, full-disk encryption, an approved applications list, and VPN configuration — and the device must remain compliant with those policies to retain access to company resources.

Conditional Access policies in Microsoft Entra ID (formerly Azure AD) work alongside Intune to ensure that only compliant, enrolled devices can reach Microsoft 365 email, SharePoint, and Teams. A non-enrolled device attempting to access corporate email will be blocked until it meets the compliance requirements. This approach means security is enforced at the point of access, not just at the device level.

Beyond MDM, a comprehensive mobile security strategy also includes Mobile Threat Defence (MTD). MTD solutions run on the device itself, scanning for malicious applications, detecting phishing links opened in mobile browsers or messaging apps, and identifying suspicious network connections — such as man-in-the-middle attacks on public Wi-Fi. When MTD detects a threat, it can automatically flag the device as non-compliant in Intune, which in turn triggers Conditional Access to block the device from corporate resources until the threat is resolved.

The Five Core Mobile Security Controls

Every UK business that issues company phones or permits staff to use personal devices for work should have the following controls in place:

1. Device Encryption

All company devices must be encrypted at rest. Modern iOS devices are encrypted by default when a passcode is set. Android devices running Android 10 or later also support full-disk or file-based encryption. Intune compliance policies can verify encryption status and block access for unencrypted devices. Encryption ensures that even if a device is physically stolen, the data on it cannot be read without the correct authentication credentials.

2. Strong Authentication

PIN-only authentication is no longer sufficient for devices that access sensitive business data. Best practice is to combine biometric authentication (fingerprint or facial recognition) with a strong alphanumeric passcode as a fallback, and to require MFA for access to cloud applications. Intune can enforce minimum PIN length, complexity requirements, and biometric settings across all managed devices.

3. Mobile Device Management Enrolment

Every device that accesses company data should be enrolled in MDM before it is issued to a member of staff. Enrolment allows the organisation to enforce security policies, deploy approved applications, monitor compliance status, and perform a remote wipe if the device is lost or stolen. Without MDM, the business has no visibility of or control over the devices accessing its data.

4. Application Management

Controlling which applications can be installed on company devices reduces the attack surface significantly. Intune allows administrators to create an approved app catalogue, block sideloading of apps from untrusted sources (particularly important on Android), and use Mobile Application Management (MAM) policies to prevent data leakage between managed and unmanaged applications — for example, blocking the ability to copy text from Outlook into a personal messaging app.

5. Remote Wipe Capability

Every business should have a tested remote wipe process in place before a device is lost — not after. For company-owned devices, a full wipe returns the handset to factory settings. For BYOD devices, a selective wipe removes only the managed work profile and corporate data, leaving personal content intact. The process should be documented, tested on a spare device, and understood by whoever is responsible for initiating it.

Why UK Businesses Need Mobile Security Controls

Mobile devices are increasingly targeted by attackers. Smishing (SMS phishing), malicious applications distributed through unofficial app stores, and man-in-the-middle attacks on public Wi-Fi are all growing threats. According to DSIT's Cyber Security Breaches Survey 2025, 43% of UK businesses experienced a cyber breach — and phishing, including attacks delivered via mobile messaging platforms, remains the most common initial attack method.

With 28% of UK employees now working in a hybrid pattern (ONS 2025), company smartphones routinely connect to home networks, hotel Wi-Fi, and mobile hotspots — all environments where the traditional corporate network perimeter offers no protection. This shift makes device-level security controls more important than ever.

Under UK GDPR, businesses are responsible for the security of personal data processed on mobile devices used for work purposes. A breach caused by an unencrypted, unmanaged device accessing company data could result in an ICO investigation and enforcement action. Cyber Essentials, the UK government-backed certification, explicitly requires that all devices accessing company data — including mobile phones — meet minimum security controls including encryption, access control, and patch management.

The cybersecurity landscape for mobile devices is evolving rapidly. Attackers now target mobile devices specifically because they are often less well-protected than laptops and desktops, yet provide access to the same corporate data. A comprehensive mobile security strategy addresses this gap by ensuring that phones and tablets receive the same level of security attention as any other endpoint in the business.

Common Mobile Security Mistakes

Even businesses that have started to address mobile security often make avoidable errors that leave gaps in their defences:

• Enrolling devices in MDM but not enforcing Conditional Access: MDM enrolment alone is not sufficient. Without Conditional Access policies in Microsoft Entra ID, an unenrolled personal device can still access corporate email by simply entering the correct username and password.
• Allowing outdated operating systems: Older versions of iOS and Android contain known, publicly documented vulnerabilities. Intune can flag non-compliant devices running outdated operating systems and restrict their access until they are updated.
• No tested remote wipe procedure: Many businesses have remote wipe configured but have never tested it. When a device is actually lost, the person responsible may not know how to initiate the wipe, or may be unsure whether to perform a full or selective wipe.
• Ignoring app sideloading on Android: Android devices can install applications from sources other than the Google Play Store. Without restrictions enforced through MDM, staff may install applications that contain malware or compromise device security.
• Treating mobile security as separate from broader IT security: Mobile devices are endpoints, and they should be managed within the same security framework as laptops, desktops, and servers. Integrating mobile security with your broader cybersecurity strategy ensures consistent policy enforcement and eliminates blind spots.

Key Considerations for UK SMEs

• Enrol all devices before they access company data: MDM enrolment should be a condition of using a company phone or accessing business systems on a personal device, not an optional extra added later.
• Enforce strong authentication: PIN alone is insufficient for high-risk accounts — biometric authentication combined with MFA provides significantly better protection against unauthorised access.
• Keep operating systems updated: Outdated iOS or Android versions contain known vulnerabilities. Intune can flag non-compliant devices and restrict access until they are updated to a supported version.
• Control which apps can be installed: Restrict device installation to approved apps and prevent app sideloading where possible, particularly on Android devices where the risk is highest.
• Prepare for device loss: Every business should have a tested remote wipe process in place, with clear documentation of who to contact, what steps to follow, and how quickly the wipe should be initiated after a device is reported missing.
• Review your mobile security posture regularly: Technology and threats evolve. A quarterly review of your mobile security policies, compliance status, and any incidents ensures your controls remain appropriate and effective.

How AMVIA Can Help

AMVIA configures and manages Microsoft Intune MDM as part of its managed mobile device management and business mobile services, including device enrolment, compliance policy configuration, Conditional Access setup, and remote wipe procedures. For businesses supplying company phones, AMVIA sources handsets and manages the entire lifecycle from provisioning to secure disposal.

AMVIA's approach integrates mobile security with broader cybersecurity services, ensuring that mobile devices are managed within the same security framework as the rest of your IT estate. Whether you need to secure a fleet of company-owned devices or implement a controlled BYOD programme, AMVIA provides the technical expertise and ongoing management to keep your mobile devices — and the data on them — protected. Call 0333 733 8050 to discuss your mobile security requirements.