CVE-2021-1677 in Azure Kubernetes Service
Summary
by MITRE • 01/13/2021
Azure Active Directory Pod Identity Spoofing Vulnerability
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Analysis
by VulDB Data Team • 10/09/2024
The Azure Active Directory Pod Identity Spoofing Vulnerability represents a critical security flaw in Microsoft Azure cloud infrastructure that affects the authentication and authorization mechanisms within Kubernetes environments. This vulnerability specifically targets the Azure Active Directory Pod Identity component, which enables Kubernetes pods to authenticate with Azure services using managed identities. The flaw allows adversaries to potentially impersonate legitimate identities and gain unauthorized access to Azure resources that are protected by these managed identities. The vulnerability stems from improper validation of authentication tokens and identity claims within the pod identity framework, creating an avenue for privilege escalation and lateral movement within cloud environments.
The technical implementation of this vulnerability occurs at the identity validation layer where the Azure Active Directory Pod Identity controller fails to properly verify the authenticity of identity claims presented by pods. When Kubernetes pods request access to Azure resources using managed identities, the system should validate that the requesting pod genuinely possesses the claimed identity. However, the flaw allows malicious actors to craft forged authentication tokens or manipulate identity claims in a way that bypasses the normal validation procedures. This occurs due to insufficient cryptographic verification and trust boundary enforcement within the identity delegation process, particularly when pods are configured to use specific managed identities for resource access. The vulnerability manifests when the system accepts identity assertions without adequate verification of the pod's legitimate claim to that identity, creating a spoofing attack surface.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can enable comprehensive compromise of cloud environments where Azure Active Directory Pod Identity is deployed. Attackers who successfully exploit this vulnerability can potentially move laterally within the Azure environment, access sensitive data stored in Azure storage accounts, databases, and other services, and escalate privileges to gain broader access to the cloud infrastructure. The implications are particularly severe in multi-tenant environments where multiple applications share the same Azure subscription or resource group, as a compromised pod could potentially access resources belonging to other applications. This vulnerability also affects compliance and audit requirements, as unauthorized access attempts may not be properly logged or detected by standard security monitoring systems, leading to potential regulatory violations and data breaches.
Organizations should implement multiple layers of defense to mitigate this vulnerability, including immediate patching of affected Azure Active Directory Pod Identity components and configuration hardening of identity delegation policies. The recommended approach involves enabling strict identity validation controls, implementing additional authentication factors, and establishing robust monitoring for suspicious identity claims or access patterns. Security teams should also consider implementing zero-trust network principles where every access request is validated regardless of the source or previously established trust relationships. Organizations should regularly audit their Azure Active Directory Pod Identity configurations and ensure that only necessary pods have access to specific managed identities. Additionally, implementing comprehensive logging and monitoring solutions that can detect anomalous identity usage patterns will help identify potential exploitation attempts. The vulnerability aligns with CWE-287 which addresses improper authentication and ATT&CK technique T1550 which covers use of valid credentials, making it a significant concern for cloud security posture and compliance frameworks.