Security researchers have discovered novel ways to identify and take advantage of Microsoft Azure Arc in business settings, which is a major advancement in cybersecurity and may reveal weaknesses in this hybrid management system.
Introduced in 2019, Azure Arc extends Azure’s native management capabilities to non-Azure resources, including on-premises servers and Kubernetes clusters, through the Azure Resource Manager for centralized control.
Unveiling Azure Arc Detection Techniques
However, a detailed technical analysis recently published reveals how adversaries can pinpoint Arc deployments by analyzing specific indicators across both Azure cloud and on-premises systems.
This discovery not only aids in reconnaissance but also positions Azure Arc as a possible vector for persistent access and privilege escalation within hybrid infrastructures.
The research highlights critical traces that expose Arc’s presence, making it a target for malicious actors.
Within the Azure environment, subtle markers such as Service Principals named “Arc Token Service” and identifiable tags like “AzureArcSPN” can be accessed even by unprivileged users through tools like ROADrecon and AzureHound.
Furthermore, Managed Identities for onboarded systems, marked by the “Microsoft.HybridCompute” identifier in their ResourceID, can be enumerated to reveal Arc-managed devices across tenants.
On the ground, on-premises systems betray Arc’s installation through specific directories such as “C:\Program Files\AzureConnectedMachineAgent,” running processes like “gc_arc_service.exe,” and deployment artifacts including auto-generated Group Policy Objects (GPOs) labeled “[MSFT] Azure Arc Servers Onboarding,” all of which serve as clear footprints for attackers conducting reconnaissance.
Exploiting Arc for Persistence
Beyond mere detection, the research dives deep into the exploitation of Azure Arc as a potent mechanism for out-of-band persistence in enterprise settings.
The findings detail how attackers can recover credentials, often hardcoded within deployment scripts or tied to misconfigured Service Principals assigned overly permissive roles like “Azure Connected Machine Resource Administrator.”
Leveraging such access, adversaries can execute arbitrary code on Arc-managed systems using features like Run Commands and Custom Script Extensions (CSEs).
These powerful mechanisms, which run in the context of NT_AUTHORITY\SYSTEM, enable remote command execution and file downloads, replicating functionalities typically associated with Azure VMs.
According to the Report, A particularly alarming revelation is the ability to deploy Arc clients to unmanaged systems, linking them to an attacker-controlled Azure tenant, thereby creating a covert channel for sustained access even in hybrid-joined environments.
This exploitation potential underscores the profound security risks embedded in Arc deployments, especially when compounded by common misconfigurations such as over-privileged Service Principals or poorly secured deployment shares.
Such oversights can facilitate a dangerous escalation from on-premises to cloud environments, bridging attack paths across hybrid infrastructures.
To counter these sophisticated threats, the researchers advocate for rigorous defensive measures, including enforcing stringent access controls, conducting periodic reviews of assigned roles, and implementing allowlisting for extensions to limit unauthorized actions.
This comprehensive study serves as a wake-up call for organizations leveraging Azure Arc, emphasizing the urgent need for robust security strategies to safeguard hybrid environments against evolving attack vectors that exploit the very tools designed to streamline management.
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