A sophisticated attack chain exploiting insecure Azure configurations can compromise an entire tenant, starting from unauthenticated access to public storage blobs.
Security researchers from Improsec detailed a 24-step attack path demonstrating how attackers escalate from anonymous access to Global Administrator privileges through misconfigured dynamic groups, service principals, and managed identities.
The attack leverages native Azure features like Automation Accounts, Key Vaults, and Cloud Shell storage, highlighting critical gaps in cloud security postures.
Attack Path Technical Breakdown
The attack progresses through five privilege stages:
- Unauthenticated Phase:
- Subdomain enumeration via MicroBurst identifies public Azure Blob Storage (
adsikkerhed.blob.core.windows.net). - Publicly accessible
test.csvThe file exposes Azure AD user credentials ([email protected]). - MFASweep confirms absent MFA/conditional access policies.
- Subdomain enumeration via MicroBurst identifies public Azure Blob Storage (
- Privilege Escalation Sequence:
- A compromised user discovers the dynamic group “AutomationAdmins” with subscription-level “Automation Contributor” rights.
- Attacker invites guest user matching group rules (
[email protected]). - Automation Account runbooks reveal service principal credentials with “Virtual Machine Contributor” access.
- Virtual Machine command execution extracts managed identity tokens for Key Vault access.
- Key Vault secrets expose “AppOwner” credentials owning an application with “Storage Account Contributor” rights.
- Final Compromise:
- Attacker modifies Cloud Shell image to execute malicious PowerShell profile.
- Internal phishing lures privileged user (
privadmin) to poisoned Cloud Shell. - Guest user gains Global Administrator rights upon profile execution.
Critical Security Recommendations
Implement these countermeasures to disrupt the attack chain:
| Attack Stage | Detection & Mitigation Strategy |
|---|---|
| Public Exposure | Block public storage access; enforce TLS 1.2+ and secure transfer; rotate keys every 90 days. |
| Credential Theft | Enable MFA universally; restrict guest invitations; audit dynamic groups for privilege assignments. |
| Lateral Movement | Monitor Run Command activity; restrict Managed Identity permissions; segment resource groups. |
| Persistence | Alert on Global Administrator role assignments; restrict Azure management to compliant devices. |
Defenders should prioritize log aggregation (Azure AD audit logs, sign-ins, Key Vault diagnostics) and enable Microsoft Defender for Cloud to detect tools like MicroBurst and PowerZure.
Segmenting subscriptions into least-privilege landing zones and eliminating credential storage in runbooks are non-negotiable for robust Azure security.
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