Transcending the trust boundaries: how a cloud pentest works
Cloud penetration testing lacks standardized methodology, focusing primarily on external interfaces while overlooking critical internal trust boundaries between tenants and providers.
Users trust cloud providers to configure and maintain IT services including data storage, with providers guaranteeing service uptime and data confidentiality. To demonstrate platform security, providers employ various strategies like bug bounty programs, internal audits, or external research teams, yet cloud pentesting methodology remains inconsistent with significant blind spots.
Most cloud penetration tests historically focus on the external layer—management consoles, customer interfaces, APIs, and network perimeters—which represents only the surface of security concerns. This approach overlooks critical internal trust boundaries that separate different levels of access and privilege within cloud environments.
Three-Layer Security Model
Cloud infrastructure can be visualized as a hotel with three security zones: the booking website (External layer), guest rooms (Overlay layer), and staff area (Underlay layer). A cloud service is truly secure only when trust boundaries between these zones cannot be breached by attackers.
The value of cloud pentesting isn't measured by the number of vulnerabilities found or successful code execution. Remote command execution in an isolated tenant container represents merely the beginning of a proper pentest, not its conclusion.
Critical Assessment Questions
Effective cloud pentesting must answer five critical questions: Can an attacker read, modify, or delete other tenants' data? Can they compromise the provider's IAM service account? Does compromising a runtime environment enable spreading attacks to other resources? Can provider internal resources be affected from low-trust segments? Is virtual environment escape possible?
A negative result is still a result. If a pentester cannot move from the tenant plane to the provider overlay, that is a valuable finding. It shows which protection boundaries work in practice and which rely only on assumptions and need additional controls.
Boundary Testing Challenges
Cloud pentesting differs from traditional system assessments because cloud platforms lack standardized technical implementations. A managed database might run in an isolated virtual machine at one provider, in a shared Kubernetes cluster at another, or in a dedicated tenant cluster at a third. This variability means pentesters must reconstruct the architecture from indirect clues when boundaries are breached.
When tenant trust boundaries are compromised, pentesters must shift from finding open ports to mapping the platform's internal structure by studying processes, network routes, certificates, service names, and agent configurations. This architectural reconstruction reveals the actual trust boundaries between components.
