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By Smitha Madhavan, Neomore Consulting Oy
If your APIs could talk, they would probably say: “A little protection, please?” 😉
In today’s digital world, APIs are the nervous system of every modern enterprise - carrying data and intelligence between systems, clouds and partners. But like any nervous system, one exposed nerve can cause a lot of pain. That is where API Security comes in - not as an afterthought, but as an ongoing discipline. And definitely not as a compliance formality, but as an essential practice to keep innovation safe, stable and trustworthy.
What Is API Security, Really?
Think of it as your digital border control. Every API request that enters or leaves your landscape should pass through a few basic checks:
- Who are you? (Authentication)
- Are you allowed here? (Authorization)
- What are you carrying? (Data validation and threat protection)
On SAP BTP, this translates to API Management policies - like OAuth 2.0 and JWT validation, threat protection against injection and XML bombs, schema validation and rate limiting. Together, these policies form the “virtual firewall” that separates your systems from the open internet.
Why Is It Important?
Because attackers love APIs. They are predictable, well-documented and often less guarded than web apps.
The OWASP API Security Top 10 lists the usual suspects: broken object-level authorization, excessive data exposure, insecure configurations, weak authentication and so on.
And in a world of hybrid landscapes - with S/4HANA Cloud/On-Prem, classic ECC systems still running strong, SuccessFactors and other HR suites, custom-built finance and procurement tools, CRM platforms, partner applications and a few legacy systems still humming quietly in the basement-- one weak link can open the door wide to data leaks, downtime and a very long week for the security team.
The cost of neglect is not just data breaches; it is loss of trust! When your APIs are secure, your business can innovate boldly- without inviting chaos.
Capabilities That Keep Your APIs Safe
SAP BTP API Management provides a robust security toolbox to guard APIs across every layer -identity, data and runtime.
- Authentication & Authorization – verify who is calling (OAuth 2.0, JWT, API Key, or Client Certificate) and what they are allowed to access through role-based or policy-level authorization checks.
- Threat Protection Policies – defend against injection attacks, malformed payloads, recursive structures and denial-of-service attempts by filtering and limiting JSON or XML content.
- Schema Validation – enforce strict data formats so only well-structured, schema-compliant messages move forward.
- Rate Limiting & Spike Arrest – manage traffic bursts and protect back-end systems from overload or misuse.
- Audit Logging & Analytics – capture who did what and when, giving complete traceability for compliance and incident analysis.
- Integration with Cloud ALM / SIEM tools – extend observability by forwarding audit events to SAP Cloud ALM or enterprise SIEM platforms.
Each of these controls is applied through lightweight, declarative policies -- tiny XML snippets right inside the API Proxy flow.
That is the beauty of API Management: the security logic lives in configuration and not in the custom code, which makes it consistent and easy to audit across environments.
If you do not want to start from scratch, SAP provides ready-to-use policy templates in the Business Accelerator Hub.
They come with pre-built logic for common scenarios - for instance, a complete XML or JSON threat-protection flow or OAuth validation sequence - so teams can get secure fast without reinventing the wheel.
A minimal security stack in API Management might look something like this:
These two simple policies already do a lot- they verify tokens and block malicious or oversized payloads. But in real projects, you would usually layer several of these controls together to cover different risks.
Think of this flow as an airport-style security gate for your APIs - each checkpoint verifies something different before letting the request board the backend flight.
The diagram below illustrates a typical pre-flow in SAP API Management, implementing multiple guardrails directly in the API Proxy before any request reaches the backend.
Diagram: Policy Editor view- API key validation, IP restriction and Basic Auth check sequence in SAP API Management (PreFlow).
- verifyAPIKey checks the ticket - your API key - to confirm the caller is legitimate.
- getAllowedIP/allowedIPCheck inspects where you’re coming from - only trusted IPs are allowed through.
- getBasicAuth/decodeBasicAuth double-checks your ID by validating credentials.
- failedAuth stops any stowaways with a clear 401 Unauthorized response.
Each policy focuses on a different layer of defense: identity, origin and credentials - working in sequence to prevent bad requests from ever reaching the backend.
Best Practices And Why Discipline Beats Drama
API security is less about fancy acronyms and more about discipline:
- Inventory everything - You can not protect what you do not know.
- Design securely from day one - Use OpenAPI linting to catch risky patterns early.
- Review regularly - Run quarterly scans and annual deep dives, not just one-off audits.
- Apply policies consistently - Threat protection and schema validation shouldn’t be optional.
- Externalize secrets - store keys in the BTP Keystore or Destination service, never in policy XML.
- Rotate secrets - A token from 2021 isn’t nostalgia; it is a vulnerability!
- Transport via CTMS - so policies stay identical across DEV/TEST/PROD.
- Monitor continuously - connect logs to SAP Cloud ALM or your company SIEM for anomaly alerts.
How Neomore Approaches It
At Neomore, we combine SAP BTP expertise with real-world know-how to help customers secure, standardize and sustain their API landscapes.
Our API Security Review & Assessment offering builds on SAP’s best-practice security policies and the OWASP Top 10 framework. It is a structured service that helps customers evaluate and strengthen every layer of their API ecosystem -- from design to deployment.
We typically deliver this in four parts:
- Structured Assessment: scanning and linting OpenAPI specs, evaluating gateway configurations and verifying runtime policies.
- Controls Review: analyzing secret management, key rotation, monitoring setup and incident workflows.
- Actionable Outcomes: providing a clear, prioritized remediation backlog and a reusable threat-protection policy pack.
- Governance Cadence: creating an annual runbook and Cloud ALM integration for re-assessment and ongoing visibility.
We partner with customers to make security practical, measurable and sustainable - ensuring that good policies actually stay enforced in production. In short, we help turn API security from a compliance checkbox into a living governance loop that is reviewed, automated and continuously improved.
In Practice
We have applied this approach across manufacturing, pulp & paper, chemicals, utilities and public-sector organizations- from securing partner APIs in API Management to integrating monitoring with SAP Cloud ALM and maintaining a clear, up-to-date inventory of APIs and interfaces across the landscape.
The outcome: secure APIs, confident deployments, cleaner audit trails and fewer late-night/weekend calls from security teams.
The Takeaway
API security is not a project. It is hygiene - like brushing your digital teeth every day.
And when it is done right, it fades quietly into the background… exactly where security should be.
Or as one of our customers once joked, “Good API security is like a winter heater- invisible when it works, critical when it doesn’t.”
Discover More About Our BTP & Security Offering