Securing the Browser Era - From Cloud to AI: A blog series on protecting the modern workspace

Browser has transformed how enterprises operate, but it has also created new opportunities for attackers. As we’ve seen in Part 1, as browsers have become indispensable with Cloud and SaaS adoption, browser native threats and attacks have also increased. Despite their central role in daily work, browsers often lack the layered security controls we expect for networks, endpoints, or applications.

This post unpacks how organizations can build defense-in-depth strategies to provide browser centric protection. 

Part 2 - From Neglected to Necessary: Building Defense in Depth for Browsers

To protect against browser-specific threats like phishing, malicious extensions, data exfiltration, session hijacking, and drive-by downloads, organizations must apply the zero trust principles to browsers.  A secure browser environment with multiple layers of defense that includes explicit verification of identity, device health enforcement, browser hardening, threat intelligence, and data protection is crucial to defend against sophisticated browser threats.  Below are the multi-layered controls, defenses, and best practices an organization can implement to combat the risk from browser threats.

Leverage an Enterprise Secure Browser

Standardizing and adopting an enterprise grade secure browser for corporate access helps in reducing the attack surface. An enterprise browser such as Microsoft Edge for Business is designed to meet the security, management, and productivity needs of organizations. Microsoft Edge for Business is independently recognized by Forrester, IDC, and industry analysts as a secure enterprise browser, delivering measurable economic value, strong Zero Trust alignment, and enterprise‑grade security. Below are some of the security features and benefits of deploying an enterprise secure browser - Microsoft Edge for Business:

• Separation of Work and Personal Data- Microsoft Edge’s automatic profile separation of work and personal uses separate caches and storage and a visual enterprise-branded icon. This allows organizations to consolidate on one browser for both work and personal needs across platforms and reduce variance, bring consistency and eliminate management overhead of separate browsers. Edge for Business requires minimal user effort on BYOD and silently applies protection with security solutions integrations.
• Centralized Manageability: All settings in an enterprise browser can be centrally configured and locked down whether the organization is cloud only, hybrid, or on premises. Enterprise browsers allow organizations to enforce consistent security controls and reduce attack surface. Features like SmartScreen in Edge protect users from threats, but enterprise versions go further by letting IT turn on additional safeguards (e.g. Edge’s JIT hardening, forced VPN, strict site isolation modes, extensions) via policy. Centralized management also makes it possible to consistently apply settings across the organization for UI elements (Ex: homepage, favorites) and deploy updates to patch vulnerabilities and install new enhancements.
• Security and Threat Protection Features:

• • Phishing and Malware Defense: Edge for Business leverages Defender SmartScreen to block malicious sites/downloads and integrates with Microsoft Threat Intelligence and Windows Security Center for enterprise visibility. SmartScreen protection is native to the browser – no extensions needed – and forms the first line of defense against web threats.
  • Process Isolation and sandboxing: Multi-process architecture, which sandboxes web content in isolated renderer processes that have limited access to the operating system. This containment means if a malicious site manages to run code, it’s much harder for it to escape the browser or infect the device, ensuring robust containment of web content.
  • Enhanced Security Mode: Disables the Just-In-Time (JIT) JavaScript compiler and enables additional OS-hardening like Hardware-enforced Stack Protection and Arbitrary Code Guard (ACG) for the browser process. By removing JIT, which is often exploited in drive-by attacks and using hardware-level safeguards, Edge greatly reduces the risk of memory corruption exploits on those sites.
  • Network and Attack Surface Protections: Microsoft Edge also incorporates various other built-in security features for safe browsing. For example, typosquatting protection thwarts phishing that relies on mistyped addresses. Automatic HTTPs feature upgrades certain HTTP connections to HTTPS, when possible, to ensure encrypted transit. The browser also monitors extension installations and detects and auto-removes malicious sideloaded extensions. In addition, Edge has a built-in password manager with password monitor that scans and alerts leaked credentials on dark web.  
  • Continuous Threat Intelligence Updates: Edge benefits from Microsoft’s threat intelligence feeds. SmartScreen’s cloud service is continually updated with newly reported phishing URLs and malware sources. Scareware\scam detector in Edge provides protection from tech support scam pages such as a fake virus alert that locks the browser. Edge will immediately break out of full-screen mode, mute audio, and display a prominent warning – even before SmartScreen has a signature for it. This client-side ML sensor also signals the SmartScreen cloud to block new scam sites faster for all users.
• Integration with Enterprise Systems: Edge for Business’s out of the box integration with Entra ID, Intune, and Defender helps secure browser with same tools that organizations leverage for protecting applications and networks. It can leverage existing solutions and features like conditional access, single sign-on, MDM/MAM to provide a smoother, more secure experience, and provides visibility of browser threats in enterprise security tools. Enterprise versions ensure that the browser can be made to fit into login flows, proxy configurations, certification environments, and other enterprise needs. This tight integration not only significantly boosts security, but it also simplifies user experience.   

Implement Layered Controls

Use multiple reinforcing defenses across identity, device, browser, network, data to provide comprehensive protection. Edge for Business natively integrates with Microsoft Security solutions and can also be integrated with third party security solutions. Below are some layered controls and best practices that can be implemented to protect from browser-based attacks.

• Require Strong Authentication: Every access request in a browser must be explicitly authenticated and authorized based on context before any corporate data is exposed. Edge for Business is natively aware of Entra ID and provides seamless Single Sign-On and supports strong conditional access rules. For managed PCs, require they are Entra joined or Intune compliant to get access; for BYOD or unmanaged devices, require MFA at minimum – and consider using “allow browser access but with limited sessions” controls to reduce what unmanaged sessions can do. Leverage risk-based policies such as - block TOR/VPN anonymity or unfamiliar countries automatically and enable new features like Token binding for high-value apps to neutralize pass-the-cookie attacks.
• Harden Endpoint & Browser: At the device level, organizations should harden both the browser application and the operating system environment in which it runs. Microsoft Defender for Endpoint fortifies the device environment in which the browser runs. It provides both preventive defenses (blocking bad sites, files, and behavior) and detective controls (alerting on anomalies, stopping post-breach actions). On enterprise-managed devices, admins can configure security baseline policies for the OS and the browser via Intune baseline policies, leverage Defender for Endpoint security features such as network filtering to block traffic to malicious domains, categorize and block web content via web filtering, detect drive-by download attacks and anomalous behavior with Defender antivirus. Defender for Endpoint’s Attack Surface Reduction (ASR) rules can be utilized to effectively shore up the OS against actions that malware from a compromised browser might attempt. Defender for Endpoint also provides the device risk signals and Intune provides device compliance status to Entra to continuously verify device health to enforce adaptive access. Microsoft Defender for Endpoint’s device inventory lists installed browser extensions and potentially unwanted apps – leverage these to audit and remove dangerous add-ons enterprise-wide.  Intune can also enforce secure browser settings on enterprise managed devices. For a BYO or unmanaged device where OS cannot be controlled, requiring the user to use Edge for Business utilizes SmartScreen, Intune App Protection to containerize that session. Keeping browsers up to date is also crucial to patch vulnerabilities in both managed and unmanaged device scenarios. 
• Enforce Secure Application Access: Treat every browser session and web application as a potential entry point for attackers. Conduct regular risk assessments and maintain an inventory of all web apps accessed by users by leveraging Defender for Cloud Apps for discovery and control. Apply granular access policies using Conditional Access, Defender for Cloud Apps, and Global Secure Access to restrict sensitive actions based on user, device, and risk context.
• Monitor network interactions and pre-empt threats: Defender SmartScreen and Network Protection in Defender for Endpoint help leverage the vast Microsoft threat intelligence to block threats. Defender for Office 365 Safe Links works in conjunction with browser security by catching phishing at the email source. Ensure web application firewalls (WAFs) are protecting any self-hosted web services. For Wi-Fi, use WPA3 enterprise to prevent local sniffing that could steal session cookies.  Secure the networks (on-prem or cloud) that connect browsers to apps through micro-segmentation. 
• Data Protection & Compliance: Edge for Business integrates with native Endpoint DLP enforcement and the ability to prevent data exfiltration through the browser. With a managed browser, companies can ensure that uploads, downloads, copy-paste, printing, watermarking, and other actions adhere to policy – crucial for compliance with regulations like GDPR, HIPAA, etc. Enable a layered approach to prevent data leaks via the browser by leveraging Purview DLP on the endpoint and in Edge, along with Defender for Cloud Apps for in-session control. On a managed device, endpoint DLP policies in Edge will directly block prohibited actions. On an unmanaged device, Conditional Access and Defender for Cloud Apps can enforce restrictions.
• Logging and SecOps: Collect telemetry from everywhere (Edge, proxies, endpoints, identity) in a centralized SIEM such as Sentinel and set up alerts for example - multiple SmartScreen blocks which could mean a user is repeatedly trying to bypass warnings. Leverage automation to respond to browser-based incidents for instance - if a browser exploit is detected, isolating the machine quickly. Use Microsoft 365 Defender’s hunting queries for proactive threat detection such as identifying any suspicious PowerShell spawned by browsers or abnormal data transfer events. 

A secure browser, coupled with defense in depth and Zero Trust offer a powerful playbook for managing today’s browser risks and becomes a powerful first line of defense for the cloud-first, work-anywhere world.

Yet, just as organizations start to catch up, a new frontier is emerging — AI-powered browsers. In Part 3, final post, we’ll look ahead at the next evolution: AI browsers. They promise new levels of productivity and insight but also open doors to sensitive data leakage, model manipulation, and other novel risks and how enterprises can strike the right balance between risk and innovation.