The Grey Cloud in the Blue Sky
- Javier Conejo del Cerro
- hace 24 horas
- 2 Min. de lectura
A misconfigured Azure setup opened a dangerous path that let attackers seize full control of a tenant’s cloud environment. The breach began when threat actors discovered a publicly accessible Azure blob container containing a CSV file with valid Azure Active Directory credentials. From this initial access, they bypassed MFA restrictions using PowerShell authentication and exploited Azure’s flexibility to move laterally. By manipulating dynamic group membership rules, attackers escalated privileges rapidly. Using harvested managed identity tokens and impersonated service principals, they ultimately reached Global Admin and User Access Admin levels—seizing control over the entire infrastructure without needing to deploy malware or exploit traditional vulnerabilities.
Online Secret Target
The attackers specifically targeted cloud-first organizations that rely on Azure for essential infrastructure. These included virtual machines, internal automation, storage services, and centralized identity management. The attack compromised high-privilege cloud shell profiles, exposed sensitive secrets in Azure Key Vaults, and disabled or hijacked administrator accounts. By poisoning trusted resources and leveraging misconfigurations, the threat actors gained deep and persistent access to systems that were considered secure.
Anatomy of a Breach
The breach chain highlights the sophistication and creativity of cloud-based attackers. It began with the reconnaissance of Azure subdomains and publicly exposed storage containers, where a CSV file containing valid credentials was discovered. Armed with these credentials, the attackers authenticated via PowerShell and bypassed MFA protections due to absent conditional access policies. Privilege escalation followed through the abuse of dynamic Azure AD groups that automatically granted roles based on user display names. A crafted guest account met the group criteria and gained contributor rights, allowing access to automation runbooks with hardcoded service principal credentials. From there, attackers harvested managed identity tokens from virtual machines to infiltrate Azure Key Vaults, impersonated privileged service principals to reach sensitive storage resources, and ultimately poisoned a trusted cloud shell image. By luring a high-privilege user into loading it, they secured Global Administrator privileges and, shortly after, full User Access Administrator control at the tenant root level.
Bring umbrellas, in case open skies turn downpour overcast
Organizations can protect themselves by closing every gap in their Azure setup. Recommended measures include:
Disable public access to storage accounts: Always configure containers to require authentication and enforce secure transfer protocols (TLS 1.2 or higher).
Harden identity management: Avoid dynamic group memberships for privileged roles and require MFA or conditional access policies at all entry points.
Restrict guest access: Limit or eliminate the ability for guest users to be invited or inherit powerful roles.
Secure secrets and automation workflows: Store secrets only in protected Key Vaults, monitor automation accounts, and never embed credentials in runbooks.
Enable full monitoring: Use Azure AD audit logs, sign-in logs, and Microsoft Defender for Cloud to detect lateral movement and impersonation attempts.
This case shows how misconfigurations, rather than malware, can lead to complete compromise. Vigilance, auditing, and secure architecture remain the strongest defense.
Comments