Securing Hybrid Identity

By Guido Grillenmeier August 04, 2022 | Active Directory

Identity is the new security perimeter. Any breach in this perimeter can enable malicious users to gain access to your apps, your data, and your business operations. For organizations that rely on Azure Active Directory or a hybrid environment of Azure AD and on-prem Active Directory to provide identity services, securing hybrid identity can be a complex and time-consuming task. Yet it’s one that’s absolutely vital.

Hybrid environments, especially, are prone to errors and misconfigurations that leave the door wide open to cyberattacks. And by compromising your on-prem Active Directory, attackers can extend their dirty work into Azure AD or vice versa. The SolarWinds attack is a prime example of this type of strategy.

The challenges of securing hybrid identities are quite different from those found in purely on-premises environments. If your infrastructure includes Azure AD—and if your organization uses Microsoft Office 365, it does—here are the top issues to guard against.

Lateral attacks from within on-premises AD

Cybercriminals often use phishing and social engineering attacks to target vulnerable users and trick them into disclosing sensitive information, including identity credentials. The SolarWinds and Colonial Pipeline attacks illustrate the risk. The threat actors in these cyberattacks gained dominance over on-premises AD, compromised the ADFS federation to forge SAML tokens, and gained access to Azure AD.

What you can do to thwart attackers when securing hybrid identity

First and most obvious, enforce MFA. Stolen identity credentials are one of cyber attackers’ most dangerous tools, and the use of those credentials can go undetected for long periods. Not all monitoring systems flag unusual account activity, so this additional layer of protection is important.

Second, understand that modern hybrid identity management calls for additional security controls beyond those available in a traditional ADFS deployment. Maintaining the necessary infrastructure to host ADFS carries its own risks, including missed patches, outdated hardware, and so on.

Instead, consider AD Pass-through Authentication, which enables use of the same password to log in to both on-premises and cloud applications. This approach uses an outbound-only connection model and certificate-based authentication to delegate the authentication process to the on-premises Active Directory, providing a more secure alternative to ADFS. You can also integrate AD Pass-through Authentication with other Azure AD security measures to guard against infiltrations and credential thefts. And you can synchronize AD password hashes to Azure AD.

You might also consider Azure AD Application Proxy, which uses Azure AD credentials to configure secure remote access to applications hosted on-premises and provides the same user experience as any Azure AD-integrated application.

Configuration creep and complexity

Hybrid identity protection complicates your job—whether you’re an AD admin, an identity pro, or a security expert. Threats are continually evolving and locking down access to your Tier 0 assets—including AD and Azure AD—is a time-consuming chore. But neglect it, and you can easily find yourself spending that time scrambling to recover AD from a cyberattack.

Using Azure AD for third-party application authentication adds complexity to the security model. In some cases, these apps can read and store data from Azure AD, extending your risk perimeter and leaving data security dependent on the third-party application with which Azure AD integrates.

Another possible weak spot is the level of permissions given to applications in Azure AD. If you don’t carefully review permission settings before granting access, these apps might end up with more permissions in Azure AD than they require. This potential oversight adds to the risk of applications making changes in the AD tenant.

And security measures like MFA might not work for some apps, making them dependent on whatever security controls the app can provide.

What you can do to tighten access

These potential security gap calls for strict governance and periodic audits of app permissions to understand where to implement additional restrictions. Tie up any loose ends and ensure that you have the right set of roles enabled in Azure AD, audit app permission settings and tighten app security configurations, and add guardrails such as MFA.

Also, evaluate the way you manage RBAC. The assignment of roles in Azure AD differs from traditional AD access management, so carefully consider how roles are defined and permissions granted.

Following the principle of least privilege is important when securing hybrid identity. Don’t add accounts that you synchronized from on-prem AD to Azure AD into a privileged RBAC role such as Global Administrators. Reserve those highly privileged roles for native Azure AD accounts. You can also create Administrative Units in your Azure AD tenant. This capability enables you to restrict the objects that IT team members can manage via a specific RBAC role, further supporting least privilege.

Misconfigurations and other security vulnerabilities

Misconfigurations and security vulnerabilities associated with your identity management solution provide access points for cyber attackers. Azure AD consists of managed services; Microsoft manages the security of its underlying infrastructure in the cloud. But the security of your data and Azure AD configuration is your responsibility.

During a cyberattack, attackers can alter or wipe out users, groups, roles, conditional access policies, and so on. Unless you have a proper recovery plan, you could be looking at a devastating and long-lasting impact. There are few native controls to protect data or configurations in Azure AD from being overwritten during an attack.

What you can do to make securing hybrid identity less complicated

The Azure AD recycle bin provides a soft delete feature that can help you restore deleted users. However, this feature has minimal capabilities to restore anything beyond a 30-day window.

Other forms of compromise can be difficult to detect and mitigate, especially if attackers move laterally from on-prem AD to the cloud. In addition to native security measures, IT leaders should explore tools with advanced capabilities to help you track attacks that could extend laterally across hybrid environments. change-tracking and auto-remediation features can protect against stolen credentials and malicious insiders. And always have a proactive, tested recovery plan for Active Directory and Azure AD.

Learn more

For more information about securing hybrid identity, see these resources.

About the author
Guido Grillenmeier
Guido Grillenmeier Chief Technologist
Guido Grillenmeier is Chief Technologist with Semperis. Based in Germany, Guido was a Microsoft MVP for Directory Services for 12 years. He spent 20+ years at HP/HPE as Chief Engineer. A frequent presenter at technology conferences and contributor to technical journals, Guido is the co-author of Microsoft Windows Security Fundamentals. He’s helped various customers secure their Active Directory environments, and supported their transition to Windows 10/m365 and Azure cloud services. Linkedin
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