Governing Security Architecture Across Hybrid ECC, S/4HANA and BTP Landscapes
Establishes an architect-level framework for governing security consistently across hybrid ECC/S/4HANA/BTP landscapes, including migration, rollback, cost and operational trade-offs.
Explanation
In a hybrid landscape where ECC, S/4HANA on-premise or private cloud, S/4HANA public cloud, and BTP coexist, security architecture cannot be designed once and left static. It must be governed continuously as an evolving system of controls spanning identity, authorization, data protection, and integration security, each with different maturity levels and constraints across deployment models. The first governance decision is establishing a single accountable security architecture owner (or governance board) who owns cross-system policy definition, even though implementation is distributed. In ECC and S/4HANA on-premise or private cloud, the customer controls authorization objects, roles, and often custom security-relevant code, giving deep flexibility but full responsibility for hardening. In S/4HANA public cloud, SAP manages the underlying platform and patches, but the customer still fully owns business role design, segregation of duties, and access governance — architects must not assume public cloud absolves them of governance discipline. BTP introduces a different model again, with platform-level trust configuration, subaccount-level identity federation, and service-specific authorization (often via scopes/role collections) that maps loosely, not identically, to ABAP-based roles. A core governance decision is how identity and trust flow across these systems. Options include: a central corporate identity provider federating into an SAP-provided identity service which then trusts each system, versus multiple disconnected identity stores per system. The federated model reduces duplication, simplifies deprovisioning, and supports faster incident response (disable once, access removed everywhere), but requires careful design of session lifetimes, claims mapping, and fallback authentication in case the central identity provider is unavailable — architects must document what happens to access during an identity provider outage, since this is a real availability trade-off. Segregation of duties (SoD) is another governance dimension that must be designed holistically rather than per-system. A conflict that spans ECC and BTP (for example, a custom BTP application that lets a user both create and approve a financial posting that ultimately reaches ECC or S/4HANA) is invisible if SoD analysis only looks inside one system. Architects must define which system is authoritative for SoD risk analysis and how extension-layer transactions are captured in that analysis, since clean core patterns often push business logic into BTP extensions that traditional on-premise SoD tools may not natively inspect. Migration and rollback governance matters especially during ECC to S/4HANA transitions. Role and authorization migration is not a lift-and-shift: many ECC transaction codes are replaced by Fiori apps with different authorization objects, so a redesign, not just a technical conversion, is required. Architects should mandate a parallel security testing phase where both legacy and new roles are validated against real business scenarios before cutover, and should require a documented rollback plan for authorization changes — for example, keeping prior role versions available and reversible for a defined window, and ensuring emergency access procedures work identically pre- and post-cutover. Operationally, security architecture governance must include monitoring and cost trade-offs. Centralized logging and SIEM integration across ECC, S/4HANA and BTP increases visibility but adds licensing, storage, and integration engineering cost; a risk-based approach — prioritizing monitoring for high-risk interfaces, privileged access, and cross-system SoD-relevant transactions — is usually more sustainable than attempting uniform full-fidelity logging everywhere immediately. Architects should also define a recurring governance cadence (e.g., periodic access recertification, role review, and trust configuration audit) rather than treating security architecture as a one-time delivery artifact, since business processes, integrations, and regulatory requirements will continue to evolve after go-live.
Real project scenario
During an ECC to S/4HANA private cloud transformation with a new BTP-based approval extension, the architecture board discovered that a manager could both raise and approve high-value purchase requisitions because the SoD tool only scanned ECC/S/4HANA roles and had no visibility into the BTP extension's role collections. The governance framework was updated to require every new BTP extension to declare its business-critical actions in a shared SoD risk register, reviewed jointly by the security architect and process owners before go-live.
Common mistakes
• Assuming S/4HANA public cloud eliminates the need for customer-owned access governance • Treating role migration from ECC to S/4HANA as a technical conversion rather than a redesign • Running SoD analysis only within individual systems, missing cross-landscape conflicts introduced by BTP extensions • Centralizing identity without documenting fallback behavior during identity provider outages • Implementing full-fidelity security logging everywhere without a risk-based prioritization, driving unsustainable cost • Treating security architecture governance as a one-time project deliverable instead of a recurring operational discipline
Best practices
• Assign a single accountable owner or board for cross-landscape security architecture governance • Document identity federation trust flows and fallback behavior during identity provider outages • Extend SoD risk analysis to cover BTP extensions and custom clean-core logic, not just core ERP roles • Require redesign, not simple conversion, of authorization roles when migrating from ECC to S/4HANA • Maintain reversible role versions and tested emergency access procedures through cutover windows • Prioritize security monitoring investment using risk-based criteria across interfaces and privileged access • Establish a recurring cadence for access recertification, role review, and trust configuration audits
Interview angle
Architect interviews often probe how candidates would design governance, not just controls, across hybrid landscapes: how they assign ownership of cross-system SoD, how they handle identity federation failure scenarios, and how they balance monitoring cost against risk. Strong answers describe explicit ownership models, documented trade-offs (not just technical mechanisms), and a recurring governance cadence rather than static, project-only thinking.