CVE-2023-21777 in Azure App Service on Azure Stack Hub
Summary
by MITRE • 02/14/2023
Azure App Service on Azure Stack Hub Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 03/15/2023
The Azure App Service on Azure Stack Hub elevation of privilege vulnerability represents a critical security flaw that allows authenticated attackers to escalate their privileges within the system. This vulnerability specifically affects the Azure Stack Hub environment where Azure App Service components operate, creating potential pathways for unauthorized access to elevated system resources. The flaw exists within the privilege management mechanisms of the App Service runtime environment, enabling malicious actors with existing user credentials to gain administrative or higher-level permissions than initially granted. This type of vulnerability directly impacts the principle of least privilege that is fundamental to secure system design and can lead to complete system compromise when exploited effectively.
The technical implementation of this vulnerability stems from improper access control mechanisms within the Azure App Service runtime environment on Azure Stack Hub. The flaw manifests when the system fails to properly validate or enforce privilege boundaries during specific operational sequences, allowing authenticated users to bypass normal permission checks and execute operations that should be restricted to privileged accounts. This typically occurs through manipulation of API calls, service interactions, or runtime execution contexts where the system does not adequately verify the requesting user's authorization level against the requested operation. The vulnerability may involve weaknesses in role-based access control implementations, insufficient input validation of privilege-related parameters, or flawed session management that permits privilege escalation through authenticated channels.
The operational impact of this vulnerability extends beyond simple privilege escalation, potentially enabling attackers to access sensitive system data, modify critical configurations, or even take complete control of the App Service environment. Once exploited, the vulnerability allows attackers to perform actions such as deploying malicious applications, accessing other users' data, modifying system settings, or creating new administrative accounts. The implications are particularly severe in cloud environments where multiple tenants share the same infrastructure, as this vulnerability could enable cross-tenant privilege escalation or allow attackers to compromise the entire shared infrastructure. Organizations relying on Azure Stack Hub for enterprise applications face significant risk of data breaches, service disruption, and compliance violations when this vulnerability is present.
Mitigation strategies for this vulnerability should focus on immediate patch deployment from Microsoft, which typically involves applying security updates to the Azure Stack Hub environment and related App Service components. Organizations must ensure that all instances of Azure App Service on Azure Stack Hub are updated to versions that contain the fix for this specific privilege escalation flaw. Additionally, implementing network segmentation and access controls can help limit the potential impact of exploitation attempts, while monitoring systems should be deployed to detect unusual privilege-related activities. The vulnerability aligns with CWE-276, which addresses improper privilege management, and may map to ATT&CK techniques such as privilege escalation through exploitation of software vulnerabilities. Organizations should also conduct thorough security assessments to identify any potential exploitation attempts and implement comprehensive audit trails to track access patterns and privilege changes within their Azure Stack Hub environments.