A manual, methodology-led assessment of your REST, SOAP, GraphQL, and backend APIs designed to identify exploitable vulnerabilities, validate business impact, and deliver evidence-based recommendations aligned with global standards and Hong Kong regulatory expectations.
Modern APIs carry authentication, payments, and business logic directly between your systems, partners, and clients. They are also the most directly exposed and least-visible part of your attack surface.
An API penetration test simulates realistic attack scenarios against your REST, SOAP, GraphQL, gRPC, and backend web services, combining automated scanning with extensive manual testing techniques. The assessment covers the endpoints your users know about, and the ones your frontend never calls but your API still exposes, including admin routes, legacy versions, and internal microservice interfaces.
APIs carry a different threat model from traditional web applications. Injection and cross-site scripting give way to authorization failures (three of the OWASP API Security Top 10), business-logic abuse, and resource-consumption attacks. Our consultants assess your APIs from anonymous external callers, across authenticated user roles, and from the perspective of a compromised partner or client integration.
Each engagement concludes with a detailed report containing prioritised findings, proof-of-concept evidence, business impact analysis, and clear remediation guidance suitable for both engineering teams and executive stakeholders.
We combine elite offensive cybersecurity expertise with institutional backing to deliver penetration testing that actually drives business resilience.
Our consultants bring deep offensive cybersecurity experience from top-tier global consulting firms, backed by the industry's most rigorous certifications including OSWE, OSCP, eWPTX, HTB CWEE, HTB CWES, and BSCP. We bring world-class execution to every API penetration testing engagement.
No junior bait-and-switch and no offshore hand-offs. The senior consultants who scope your engagement are the ones executing the test, walking you through findings, and validating your remediation. You get the same expert from kickoff through closure.
Penetration testing requires absolute trust, you are granting access to your most sensitive systems. We are proudly supported by the HKSTP Incubation Programme and the CityU HK Tech 300 Seed Fund, making us a vetted Hong Kong cybersecurity partner with institutional accountability.
We don't deliver 200-page scanner reports. Every penetration testing engagement produces prioritised findings, attack-path narratives, proof-of-concept evidence, and remediation guidance, translated for both your engineers and your board.
Clients engage us when assurance has to be independent, findings have to be actionable, and the outcome has to hold up to auditors, regulators, partners, customers, and the board.
Teams preparing to release a new API product, a public API surface, or a major version, and requiring independent assurance before partner or customer exposure.
Organisations preparing for PCI DSS, ISO/IEC 27001, SOC 2, HKMA C-RAF, SFC cybersecurity examinations, or Open API framework readiness that require independent testing of API interfaces.
Organisations onboarding new partner integrations, opening data-sharing interfaces, or operating as an API provider whose external clients expect documented security assurance.
Organisations re-validating security posture following a reported incident, control failure, or significant architectural change.
Engineering and security teams seeking third-party verification following internal testing, bug bounty programmes, or remediation cycles.
Acquirers and investors evaluating the security posture of target organisations' APIs and backend services prior to transaction close.
Every engagement is scoped collaboratively to ensure testing objectives align with business priorities, risk appetite, and regulatory context.
Coverage is structured around the OWASP API Security Top 10 (2023), the OWASP Web Security Testing Guide (WSTG), and CWE Top 25. The domains below highlight our core focus areas, but our complete coverage extends far beyond them.
Endpoint enumeration from specifications, client traffic captures, and blind probing to map the complete API inventory, including shadow routes, legacy versions, unauthenticated debug endpoints, and services your own team may have forgotten are still live.
Assessment of authentication schemes including OAuth 2.0, OpenID Connect, JWT, API keys, mutual TLS, and HMAC signatures. Review of token generation, lifetime, rotation, and revocation, and resistance to forgery, replay, and downgrade.
Rigorous testing for Broken Object Level Authorization (BOLA), Broken Object Property Level Authorization (BOPLA), and Broken Function Level Authorization (BFLA), the three authorization failures behind the majority of real-world API breaches. Horizontal and vertical privilege escalation, multi-tenant isolation, and cross-account access validated across every authenticated role.
Parameter fuzzing, schema abuse, mass assignment, and injection testing across every discovered endpoint. Coverage includes SQL, NoSQL, command, template, XML External Entity (XXE), and server-side request forgery (SSRF), with particular attention to deserialization and file-upload paths.
Workflow and business-rule abuse including race conditions, multi-step sequence manipulation, quota bypass, and sensitive-business-flow attacks such as coupon stacking, price manipulation, and enumeration through legitimate endpoints. Rate-limit bypass, batch abuse, and denial-of-wallet testing against metered or pay-per-use services.
Transport-layer security, certificate handling, header security, CORS configuration, error-message hygiene, and information disclosure through verbose responses. Review of upstream APIs your service consumes, including trust assumptions made about third-party responses and data returned from integrations.
A structured, repeatable methodology that delivers consistent quality, with clear entry and exit criteria at each phase and defined responsibilities on both sides.
Define target surface (public, partner, or internal APIs), ingest specifications and schemas where available, agree test credentials across roles, communication protocols, and rules of engagement. Gather documentation, confirm authority to test, and agree on the delivery model.
Combined automated scanning and extensive manual testing across the full API attack surface, including endpoints the frontend never calls. Critical issues are escalated in real time. All findings are manually verified to eliminate false positives.
A detailed technical report with executive summary, risk-rated findings, business impact analysis, proof-of-concept evidence, and prioritised remediation recommendations.
A structured walk-through of the findings with your technical team, covering issue context, exploitation impact, and remediation guidance. Support for clarification during fix implementation.
Retesting of remediated findings against an updated API version or environment to confirm fixes are effective, followed by an updated risk posture and formal engagement closure. Deliverables are packaged for internal follow-up, audit, and regulatory evidence.
Every engagement produces a comprehensive report designed to serve both technical remediation and executive decision-making.
A non-technical overview of the assessment, key findings, business impact, and recommended priorities, written for leadership, risk, and board-level stakeholders.
Each finding documented with technical description, affected components, exploitation steps, observed impact, and references to relevant standards.
Findings are rated using the Common Vulnerability Scoring System (CVSS) and the OWASP Risk Rating Methodology, combined with business-context adjustments to reflect realistic risk to your organisation.
Screenshots, request/response captures, and step-by-step reproduction details that demonstrate each critical and high-severity issue without ambiguity.
Clear, prioritised recommendations mapped to each finding, including short-term containment and longer-term architectural improvements where applicable.
Every finding is mapped to OWASP, CWE, and where relevant, to regulatory frameworks. This supports audit, compliance evidence, and internal knowledge transfer.
Our methodology is built on internationally recognised API testing standards and mapped to the compliance frameworks most relevant to Hong Kong-regulated organisations.
API penetration testing covers a different threat model from traditional web testing. Web pentests focus heavily on injection, cross-site scripting, and user-facing flows that reach the application through a browser. APIs remove the browser, remove the frontend's business rules, and expose every endpoint directly to anyone who discovers the URL. The attack surface is larger, flatter, and more programmatic. The dominant failure modes shift accordingly: authorization flaws (Broken Object Level Authorization, Broken Object Property Level Authorization, Broken Function Level Authorization) account for more real-world API breaches than injection ever does, and business-logic, resource-consumption, and schema-manipulation attacks take on far greater weight. The methodology, tooling, and test coverage differ accordingly.
We can perform a complete assessment with no documentation, relying on blind discovery, traffic capture from your own clients, and iterative endpoint probing. This is our default black-box posture. Where an OpenAPI specification, Swagger UI, Postman collection, WSDL file, or GraphQL schema is available, coverage and efficiency improve materially, particularly for authorization and business-logic testing, which benefit from understanding the full inventory of roles and objects the API exposes. The engagement mode is agreed with you during scoping.
Yes, and for APIs it matters more than it does for traditional web applications. API gateways and WAFs can enforce authentication, rate limits, and generic input filtering, but they do not validate business logic, they do not understand the authorization boundaries between your users and their data, and they cannot detect whether a legitimately authenticated caller is accessing objects they should not have access to. The majority of exploitable API findings we report are authorization and business-logic flaws that are invisible to gateways, WAFs, and automated scanners by design.
We recommend the mode based on your objectives, available documentation, and coverage expectations. Black-box mirrors an external attacker discovering the API from nothing, which is realistic but time-constrained and likely to miss documented-but-undisclosed surfaces. Grey-box provides partial documentation and credentials for one or more roles, and balances realism with efficiency; it is our most common choice for authenticated APIs. White-box offers full specifications, schemas, credentials across roles, and architectural documentation to maximise depth and coverage. For authorization-heavy APIs, grey-box at minimum is strongly recommended so that role-based access controls are fully validated.
All engagements are led by senior offensive security consultants. We do not assign junior operators or outsource execution to third parties. Our consultants hold recognised industry certifications across offensive security and red teaming, including credentials such as OSCE³, OSEP, OSWE, OSCP, HTB CPTS, HTB CWEE, eCPTX, CRTO, and CRTP. Every assessment is reviewed by a senior lead before delivery, ensuring consistent technical depth and reporting quality regardless of which consultant is assigned.
Duration depends on the API surface area, business-logic complexity, and engagement mode. As a general guide, a focused API assessment in grey-box mode typically runs 5 to 10 business days of active testing, plus 3 to 5 days for reporting and review. Larger API programmes, microservice architectures, or full white-box assessments extend further. An accurate estimate is provided during the scoping call based on your specific surface and objectives.
Most engagements kick off within 1 to 2 weeks of scoping sign-off, subject to consultant availability and the agreed testing window. Where a regulatory deadline or pre-launch milestone requires a faster start, we will do our best to accommodate and confirm feasibility during the scoping call.
Testing is designed to be non-disruptive. Before execution, we agree on the testing window, excluded actions (e.g. destructive payloads against live data, uncontrolled rate-limit saturation), and real-time escalation protocols. Where a dedicated staging environment and test accounts can be provided, testing runs in isolation with no impact on live users. Where testing must be conducted against a live API or live data, we coordinate higher-risk techniques in advance and maintain a dedicated communication channel throughout the engagement. Where you operate a SOC, SIEM, or active monitoring tooling, we share testing source IPs, timing, and signatures in advance so your security team can suppress or contextualise the resulting alerts rather than triaging them as live incidents.
Any sensitive data encountered is handled under strict confidentiality. We do not extract, retain, or reproduce sensitive data beyond what is strictly necessary to evidence a finding, and where possible, data is anonymised in the final report. Credentials provided by you for authenticated testing are held in access-controlled secrets management throughout the engagement, used only for the agreed scope and duration, and confirmed destroyed in writing after engagement closure. All engagement artefacts, including intercepted request/response captures and API specifications, are stored in access-controlled environments, transmitted over encrypted channels, and securely destroyed after the agreed retention period.
Yes. A complimentary retest is included with every engagement. After you have applied remediation and provided an updated API version or environment, we re-examine each confirmed finding to verify that fixes are effective and that no regressions have been introduced, and issue an updated report reflecting closure status for each item. The retesting window is agreed with you during scoping to align with your remediation plan.
Yes. On request, we issue a formal Letter of Attestation summarising the engagement scope, testing period, methodology followed, and high-level outcome. The attestation is suitable for audit, regulatory submission, and third-party assurance purposes, including PCI DSS, SOC 2, ISO/IEC 27001, and HKMA-related obligations.
Schedule a scoping call with our specialists to define the right engagement model for your APIs, regulatory context, and timeline. We will walk you through methodology, deliverables, and next steps.