Beyond SOC 2 and ISO 27001: A Technical Guide to Securing Third-Party APIs in SaaS Environments
Why Traditional Certifications Don’t Secure SaaS APIs
In today’s cloud-native landscape, enterprises are doubling down on Software as a Service (SaaS) to scale faster, innovate continuously, and reduce infrastructure overhead. But behind the scenes of every connected SaaS solution is a complex web of Application Programming Interfaces (APIs)—bridges that facilitate functionality, data exchange, and interoperability across internal systems, partner platforms, and third-party services.
While APIs are essential for modern agility, they also introduce unprecedented security risk. As APIs become the new surface area for digital business, they also become the primary target for attackers—from token abuse and injection flaws to excessive data exposure and broken object-level authorization. And the risk doesn’t stop at your perimeter. In API-driven SaaS ecosystems, third-party APIs often process, transmit, or even control access to sensitive data on your behalf.
Yet most organizations rely on SOC 2 Type II or ISO/IEC 27001 as proxies for security maturity in their vendor assessments. These frameworks are helpful starting points—but they were not designed to assess or mitigate real-time API threats, dynamic third-party integrations, or runtime behaviors of service architectures built on APIs. They offer static, checkbox-based evaluations that miss the evolving, deeply technical nature of API attack surfaces.
To close this gap, organizations need more than compliance. They need a new playbook—one built on continuous validation, API-aware risk management, and secure-by-design principles.
In this technical deep dive, we break down:
Why APIs are high-value targets and risk multipliers in modern SaaS environments
The limitations of SOC 2 and ISO 27001 in protecting API-driven integrations
A comprehensive approach for evaluating third-party APIs using technical, contractual, and operational controls
How to implement continuous monitoring, real-time detection, and response capabilities for APIs
When and how to move beyond certifications using OWASP API Security Top 10, runtime validation, and threat intelligence
If your GRC program still treats APIs as traditional infrastructure endpoints—or assumes third-party certifications equal API security—you’re already exposed. This guide helps you close that gap with a modern, defensible, and risk-aligned strategy for third-party API assurance.
Understanding the Risk: Why APIs Are Security Multipliers in SaaS
APIs expose backend services and data structures to external systems, often over public or semi-trusted networks.
This makes them a prime target for attackers, especially in multi-tenant SaaS ecosystems where sensitive data and service orchestration are API-dependent.
Key Threat Vectors in API Ecosystems:
Injection Flaws (SQL, NoSQL, XML)
Broken Object-Level Authorization
Inadequate Rate Limiting and Throttling Controls
Insecure Data Serialization and Deserialization
Unprotected Sensitive Data Exposure
Third-party API Supply Chain Compromise
Business Context: A fintech startup integrating a third-party KYC (Know Your Customer) service via API could inadvertently expose personal identifiable information (PII) if API security headers or authentication flows are misconfigured.
Phase 1: Third-Party Security Vetting Beyond the Checklist
A high-level review of SOC 2 Type II and ISO/IEC 27001 reports is no longer sufficient for SaaS organizations relying on complex, API-driven integrations with third-party service providers.
These certifications provide a generalized view of a provider’s security posture but lack the specificity, depth, and API-focused assurance required in today’s API-centric environments.
A more granular and technically aligned assessment is necessary to properly vet external vendors.
1.1 Go Deeper Than the Audit Reports
Limitations of SOC 2 Type II in API Context:
SOC 2 Type II reports primarily address five Trust Services Criteria: Security, Availability, Processing Integrity, Confidentiality, and Privacy. However, these criteria are interpreted through a general control lens, meaning:
They rarely cover token lifecycle management (e.g., rotation intervals, revocation procedures).
Scope-based authorization mechanisms (e.g., RBAC or ABAC implementations at the API level) are not explicitly evaluated.
Granular security configurations (e.g., API rate limiting, throttling enforcement, replay attack protections) are often not assessed.
Testing results are usually omitted—reports summarize control design and effectiveness without disclosing raw data or findings.
Limitations of ISO/IEC 27001 in API Context:
ISO 27001 focuses on establishing an Information Security Management System (ISMS), ensuring that organizations have policies and processes to manage information risks. However:
ISO 27001 does not mandate validation of specific technical controls—especially those relevant to runtime API behavior or microservice exposure.
There's no requirement for continuous testing or dynamic runtime analysis of APIs.
Controls related to DevSecOps integration, such as secure API design in CI/CD pipelines or runtime enforcement in containers, are not directly addressed.
Recommended Actionable Steps:
Request API-specific penetration testing results, including test scope, tooling used (e.g., Burp Suite, ZAP, Postman), and identified vulnerabilities (e.g., BOLA, injection flaws).
Obtain API security architecture documentation, including:
Authentication flows (e.g., OAuth2.0 grant types in use)
Token issuance and expiration policies
Response filtering techniques (e.g., field-level masking)
Secure transport configurations (e.g., TLS enforcement, mutual TLS setup)
Request sample OpenAPI/Swagger specs to validate endpoint exposure, input validation rules, and security schema definitions.
Verify control coverage with questionnaires or technical interviews focused on API security implementation, rather than generic security management processes.
1.2 Focus on API-Specific Compliance
Why Generic Compliance Isn’t Enough:
Traditional compliance programs are often written at the application or data-center level. They seldom break down API-specific risks, such as:
Broken Object-Level Authorization (BOLA): APIs exposing object IDs without adequate permission checks.
Excessive Data Exposure: APIs returning more data than necessary, violating data minimization principles.
Improper Asset Management: Orphaned or undocumented APIs (a.k.a. “shadow APIs”) not included in the compliance scope.
Standards and Mapping:
Ensure the third-party explicitly aligns its API design and security controls with the OWASP API Security Top 10. Request a formal mapping document or control matrix that illustrates which of the Top 10 are mitigated and how.
For providers processing personally identifiable information (PII), request documentation that maps API data flows to applicable regulatory requirements, such as:
GDPR: Demonstration of data minimization, lawful basis for processing via APIs, and handling of data subject rights (e.g., delete or export requests through APIs).
HIPAA: API endpoints handling PHI must ensure data-at-rest and data-in-transit encryption, access controls, and audit logging.
CCPA/CPRA: Ensure API interactions with California consumers support required opt-out and data transparency mechanisms.
Actionable Due Diligence Practices:
Request Data Flow Diagrams (DFDs) and API Inventory Lists that include endpoint classification (public/internal), sensitivity (e.g., PII, financial data), and data destinations.
Validate the existence of API-level access logs, audit trails, and monitoring that would support compliance audits.
Ensure the provider’s data handling and storage practices meet regional compliance requirements through APIs specifically, not just at the application level.
Phase 2: Deep Technical Validation of Third-Party APIs
Third-party integrations via APIs introduce a high degree of surface area for exploitation, especially when embedded within critical SaaS workflows.
This phase focuses on validating that third-party APIs are built and operated using secure-by-design principles, properly maintained across their lifecycle, and resilient against runtime attacks and data leakage.
2.1 Secure API Development and Deployment Practices
Proper API security begins in the development phase. To ensure third-party providers are not exposing your environment to poorly designed or inadequately tested APIs, evaluate their adherence to secure development and DevSecOps principles.
Shift Left Testing
Security testing must be embedded early in the software development lifecycle (SDLC), particularly in CI/CD pipelines.
OWASP ZAP: Automate baseline API scans against staging environments to detect:
Broken authentication mechanisms
Insecure HTTP methods (e.g., TRACE, PUT)
Missing security headers (e.g., CORS misconfigurations)
Burp Suite (Enterprise or Professional): Perform authenticated dynamic analysis to detect complex logic flaws and authorization bypasses. Support for scanning OpenAPI-based APIs and fuzzing input parameters is essential.
Postman Fuzzer/Newman CLI: Use Postman's scripting and test assertion features to integrate negative and boundary condition testing directly into build pipelines.
Validation: Confirm the vendor has CI/CD pipelines that include security gates and fail builds when known API vulnerabilities (e.g., BOLA, excessive data exposure) are detected.
Code Reviews (Where Possible)
While access to source code may be limited, strong third-party providers should allow for:
Independent or internal code review documentation demonstrating:
Input validation and output encoding at every API endpoint
Logging best practices (e.g., redaction of credentials, no sensitive data in logs)
Insecure deserialization protections to mitigate remote code execution risks
If direct code access isn’t feasible, request SDLC documentation or security checklists used by their internal development teams.
API Schema Analysis
Validate the presence and completeness of OpenAPI 3.0 (or Swagger 2.0) specifications, covering:
All public and internal endpoints
Request and response payload structures
Supported authentication mechanisms per endpoint
Parameter validation (e.g., regex, required fields, types)
Automated tools (e.g., 42Crunch, Spectral, Swagger Editor) can be used to lint OpenAPI specs and detect:
Overly permissive wildcard responses (
*)Absence of defined security schemes
Lack of response filtering for PII
Use Case: APIs offering customer profile data must not expose social security numbers or full credit card PANs—even when endpoints are authenticated.
2.2 Runtime and Transport Layer Security
After deployment, APIs must enforce strong encryption, token-based authorization, and integrity controls to prevent MITM attacks, token abuse, and unauthorized access.
Transport Layer Security
Require TLS 1.2 or higher across all external and internal API endpoints.
Validate use of modern cipher suites (e.g., TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).
Ensure certificate pinning is supported for client SDKs or mobile integrations, where applicable.
For service-to-service communication, enforce mutual TLS (mTLS):
Requires both client and server to present certificates.
Validates identity at the transport layer, supplementing application-level auth.
Supports zero-trust internal API architectures.
Validation: Request SSL Labs reports or configuration samples showing TLS enforcement, preferred cipher suites, and certificate expiration policies.
JWT Token Integrity
JSON Web Tokens (JWT) are common in OAuth2/OpenID-based authorization flows. Assess the implementation details for security gaps.
Algorithm enforcement: Ensure usage of strong algorithms like RS256 or ES256. Reject tokens using
noneor symmetric algorithms without validation.Signature validation: Confirm that the token signature is verified before any data extraction or logic execution.
Expiration enforcement: Short token lifespans (<15 minutes) and support for refresh tokens is recommended. Implement token revocation lists or blacklisting where long-lived tokens are used.
Misimplementation Example: Accepting unsigned tokens (alg: none) or failing to validate audience (aud) or issuer (iss) claims creates critical vulnerabilities.
Encryption of Data at Rest
Even though APIs are generally concerned with data in transit, any persistence of sensitive data by the third party must adhere to encryption best practices.
AES-256 encryption: Verify that sensitive data such as PII, financial data, or healthcare data is stored encrypted using AES-256 or equivalent.
Secure Key Management: Ensure keys are:
Stored separately from encrypted data
Rotated regularly
Managed via enterprise-grade KMS systems (e.g., AWS KMS, Azure Key Vault, HashiCorp Vault)
Additional Considerations:
Logs containing sensitive data must also be encrypted or redacted.
Backups and staging data should follow the same encryption controls.
Phase 3: Contracts and SLAs That Reflect API Risk
Contracts and Service Level Agreements (SLAs) with third-party service providers must reflect the unique security, reliability, and compliance challenges of API integrations.
While general IT vendor agreements may include broad language about uptime or data protection, they often fall short in defining enforceable controls specific to API security, performance, and breach response.
Embedding API-centric requirements in contracts provides not only legal recourse but also drives shared accountability and security transparency.
Key Contractual Elements
1. API Rate Limiting & Throttling
Why It Matters:
Unrestricted API access can lead to resource exhaustion, denial-of-service (DoS) attacks, or unintended billing spikes. Rate limiting is also critical for controlling abuse from automated scripts or credential stuffing attempts.
Contract Language Should Specify:
Request volume limits per API key or user/IP over defined intervals (e.g., 1,000 requests/minute).
Burst handling rules and maximum concurrency thresholds.
Obligations for the provider to implement adaptive rate limiting based on behavioral analysis.
Penalty clauses or remediation requirements if excessive traffic from their systems impacts availability.
Example Clause:
“Third-party shall enforce API rate limiting of no more than 1,200 requests per minute per API key and provide automated throttling responses with HTTP 429 status codes.”
2. Authentication Mechanisms
Why It Matters:
Insecure authentication methods, such as static API keys or token reuse, expose APIs to unauthorized access, impersonation attacks, and privilege escalation.
Contract Requirements Should Include:
Mandatory use of OAuth 2.0 or OIDC flows with client credential rotation.
Support for mutual TLS (mTLS) for service-to-service authentication in internal or high-trust zones.
Requirements for automatic API key/token expiration, rotation mechanisms, and revocation processes.
Multi-factor authentication (MFA) for developer portals or privileged access to API configuration interfaces.
Example Clause:
“The Provider must implement OAuth 2.0 authorization using PKCE and short-lived access tokens (≤15 minutes). All long-lived refresh tokens must be revocable via API and managed with key rotation every 90 days.”
3. Incident Disclosure Timelines
Why It Matters:
A breach or vulnerability in an API exposed by a third-party provider may have downstream impacts on your environment and users. Delays in disclosure can compound legal, reputational, and operational damage.
Contract Language Should Require:
Mandatory notification within 24 hours of detection of any security incident affecting APIs, API traffic, tokens, credentials, or exposed data.
Detailed incident reporting requirements, including:
Affected APIs and endpoints
Timeframe and duration of exposure
Root cause analysis (RCA)
Mitigation steps and timelines
Real-time collaboration expectations during forensic investigation and containment.
Example Clause:
“In the event of an API security incident involving unauthorized access, data leakage, or system compromise, the Provider shall notify the Client within 24 hours of detection and provide full incident details and RCA within 5 business days.”
4. Audit and Penetration Testing Rights
Why It Matters:
Relying solely on vendor-provided attestations (e.g., SOC 2 reports) limits your visibility into the actual security posture of APIs in production. Direct audit and testing rights empower you to validate claims, especially after a change in service, architecture, or personnel.
Contractual Provisions Should Cover:
Annual security review rights, including API-specific configuration reviews and documentation access.
Permission to conduct third-party penetration testing of public-facing API endpoints, either independently or jointly.
Requirement that the provider performs regular third-party security assessments and shares executive summaries or redacted reports.
An obligation for remediation of critical or high-risk findings within a defined timeframe (e.g., 15–30 days).
Example Clause:
“Client reserves the right to conduct annual penetration testing on externally exposed APIs and may request redacted third-party security assessment reports upon demand. Provider shall remediate identified critical vulnerabilities within 15 calendar days.”
Phase 4: Continuous Monitoring and Threat Response
Monitoring and responding to API-level threats in real time is essential for maintaining operational resilience and minimizing blast radius in the event of malicious activity. Traditional network or endpoint monitoring is insufficient for APIs, which require contextual, protocol-aware visibility into the behavior of requesters, data flows, and identity mechanisms.
This phase focuses on embedding continuous observability and automated response mechanisms into your API landscape through purpose-built security tools and analytics platforms.
4.1 Real-Time API Security Monitoring
To manage security at the point of entry, organizations must implement API gateways that provide native enforcement of security policies and traffic analytics.
✅ Deploy API Gateways to Establish a Security Control Plane
Use solutions such as Google Apigee, Kong Gateway, or AWS API Gateway to:
• Throttle Traffic
Implement rate limiting, burst control, and quota management per token, client, or IP address.
Use dynamic throttling policies that adjust thresholds based on user behavior or business risk classification (e.g., sensitive vs. non-sensitive APIs).
• Enforce Authentication and Authorization Policies
Mandate OAuth 2.0, JWT validation, or API key restrictions at the gateway layer.
Use context-aware policies: restrict access by IP, device fingerprint, or geo-location.
• Log Request/Response Payloads for Security Analytics
Enable deep logging of API metadata:
Request method, URI, headers, and query params
Response status codes
Token claims (user ID, scopes, expiration)
Avoid logging sensitive payload data (e.g., PII, credentials) unless properly redacted or encrypted.
• Integrate with Downstream Security Controls
Feed logs into centralized logging platforms (e.g., Amazon CloudWatch, Fluentd).
Forward events to SIEM or XDR platforms for real-time analysis (see Section 4.2).
Best Practice: Tag API endpoints with classification labels (e.g., pii:yes, critical:true) and assign custom monitoring thresholds based on data sensitivity.
4.2 SIEM and Threat Intelligence Integration
Real-time visibility is amplified when API telemetry is centralized, normalized, and correlated against known threats or behavioral baselines using Security Information and Event Management (SIEM) platforms.
✅ Ingest API Telemetry Into a SIEM (e.g., Splunk, Azure Sentinel, QRadar)
Log Data Sources:
API gateway logs (from Apigee, Kong, AWS)
Web server logs (e.g., NGINX, Envoy proxies)
Identity provider logs (e.g., Okta, Azure AD tokens)
Correlation Rules to Configure:
Token Reuse Anomalies:
Repeated use of an expired or revoked token
Simultaneous usage of the same token from multiple geolocations
Unusual HTTP Methods:
POST requests to endpoints typically using GET
Use of OPTIONS, DELETE, or PATCH on sensitive APIs without precedent
Geographic or Volume Anomalies:
Spike in access from unusual geographies
Sudden traffic increase to a single endpoint outside of business hours
Alerting Mechanism:
Define priority levels and map alerts to incident response playbooks.
Integrate with ticketing or SOAR systems (e.g., ServiceNow, Palo Alto Cortex XSOAR).
✅ Integrate External Threat Intelligence for API-Specific Risks
Purpose: Enhance detection and response capabilities with enriched threat data, particularly indicators relevant to API-targeted attack campaigns.
Recommended Threat Intelligence Providers:
Recorded Future: Provides high-confidence IOCs (Indicators of Compromise) for known API attack tools, IP addresses, and TTPs (tactics, techniques, procedures).
ThreatConnect: Offers integration with MITRE ATT&CK and threat modeling for mapping observed API threats to known adversaries.
Mandiant Threat Intelligence: Delivers contextual threat actor profiles and API exploit toolkits used in recent breach campaigns.
Use Cases:
Auto-block or alert when incoming API requests originate from IP addresses in threat intelligence feeds.
Flag requests with user agents or HTTP headers known to be used by reconnaissance or exploit tools.
Update WAF rules and API gateway policies dynamically based on threat intelligence insights.
Automation Tip: Use a threat intelligence platform with STIX/TAXII support to automate feed ingestion and IOC matching.
Phase 5: Incident Readiness & Resilience
Modern SaaS environments heavily reliant on third-party APIs require tailored incident response (IR) capabilities that go beyond generic enterprise breach protocols.
Due to the dynamic nature of APIs—rapid deployment cycles, external dependencies, token-based authentication, and sensitive data flows—incident readiness must be precise, automated, and integrated with the unique behaviors and lifecycles of APIs.
This phase ensures your organization can detect, contain, mitigate, and recover from API-related incidents, including both internal faults and third-party breaches.
API-Specific Runbooks: A Structured Response Plan
Develop and maintain dedicated API incident response runbooks that align with your broader security operations playbooks but include API-layer specificity.
Containment
Containment in the API context focuses on isolating or disabling compromised components before further damage spreads.
Key containment actions include:
Token Revocation and Rotation:
Immediately revoke access and refresh tokens associated with compromised clients or user accounts.
Disable affected client credentials or API keys and rotate them using emergency procedures.
In environments using OAuth2 or OpenID Connect, leverage token introspection or revocation endpoints.
Throttling or Blocking at the API Gateway:
Dynamically update throttling policies or IP blocklists in gateways like Apigee or AWS API Gateway to cut off malicious traffic.
Apply circuit-breaker policies to isolate misbehaving endpoints or services.
Disable Compromised Endpoints:
Use feature flags or route management tools (e.g., Kong’s traffic control plugins) to temporarily disable vulnerable or exploited endpoints.
Eradication
Once immediate containment is achieved, the goal is to eliminate the root cause of the incident—often involving code, configuration, or integration issues.
Key eradication actions include:
Patch Deployment:
Apply hotfixes or full deployments to remediate vulnerabilities in API logic, such as fixing BOLA (Broken Object-Level Authorization) or input validation flaws.
Prioritize CVEs related to third-party SDKs or libraries used in API integrations.
Authentication Policy Hardening:
Strengthen token issuance lifecycles, tighten scopes, or enforce audience (
aud) and issuer (iss) claim checks in JWTs.Remove or sunset legacy authentication mechanisms (e.g., static API keys, Basic Auth).
Configuration Remediation:
Review and sanitize exposed configuration files, OpenAPI definitions, and route mappings.
Enforce stricter validation rules in schemas and gateway policies.
Recovery
The recovery phase focuses on restoring services and data integrity while ensuring the vulnerability cannot be re-exploited.
Key recovery actions include:
Restore API Configurations and Policies:
Roll back to last known good configurations using version-controlled API gateways or IaC tools (e.g., Terraform, CloudFormation).
Validate that re-deployed APIs are aligned with hardened security policies (rate limits, scopes, input filtering).
Data Restoration (if applicable):
If an API breach resulted in data loss or tampering, initiate recovery procedures using encrypted backups.
Conduct data integrity checks and re-ingestion processes for any affected downstream systems.
Security Validation Post-Restoration:
Perform post-incident penetration testing or red-teaming to validate that remediation steps have closed the exploited vectors.
Include automated regression testing in CI/CD to ensure patched APIs do not reintroduce broken functionality.
Joint Tabletop Exercises with Third-Party Vendors
Due to shared risk in API integrations, it is critical to proactively simulate breach scenarios involving third-party providers.
These exercises validate not only technical response plans but also communication protocols and legal obligations.
Tabletop Exercise Design:
Scope: Focus on scenarios such as:
Compromise of a third-party authentication service API (e.g., OpenID provider)
Credential stuffing attack exploiting an exposed API login endpoint
Data exposure from a misconfigured third-party API response
Participants:
Internal stakeholders: Security operations, DevOps, Legal, GRC, Product teams
External stakeholders: Vendor security lead, customer success/partner liaison
Objectives:
Validate API-specific incident escalation paths and 24/7 contacts
Test the third party’s ability to provide logs, token telemetry, and RCA within SLA timelines
Review notification workflows for regulators and affected customers (e.g., GDPR Article 33 requirements)
Outputs:
A formal post-exercise report identifying gaps in preparedness, documentation, communication, and tooling
Updated runbooks and SLAs incorporating lessons learned
Timeline for remediation or control improvements to close gaps uncovered during simulation
Why SOC 2 and ISO 27001 Fall Short in API Security
SOC 2 and ISO/IEC 27001 remain foundational certifications for establishing trust in a service provider’s overall information security posture. However, when applied to API-heavy SaaS architectures, these standards do not adequately address the dynamic, technical, and operational risks inherent to API ecosystems.
Modern APIs introduce attack surfaces that evolve rapidly, operate in distributed cloud-native environments, and demand continuous, contextual security controls.
Neither SOC 2 nor ISO 27001 were designed with these API-specific threat vectors in mind.
1. Lack of Focus on API Runtime Behavior and Dynamic Testing
🔍 The Gap:
Both SOC 2 and ISO 27001 primarily focus on organizational controls, policies, and point-in-time evaluations rather than continuous technical validation of runtime behavior.
SOC 2: Emphasizes the existence of controls (e.g., logical access, change management), but does not require dynamic security testing of APIs (e.g., DAST, fuzzing, runtime behavior analysis).
ISO 27001: Focuses on the presence of an Information Security Management System (ISMS), but leaves out API-specific behaviors like endpoint-level access controls, token misuse, or rate limiting enforcement.
Example Limitation:
A SOC 2-certified vendor could have no API rate limiting in production, or could expose insecure public API endpoints—yet still pass the audit if broader organizational policies are in place.
2. Absence of Continuous Monitoring and Anomaly Detection Requirements
🔍 The Gap:
API threats are highly dynamic. Token abuse, credential stuffing, and excessive data exposure can occur within seconds and require real-time monitoring and automated response.
Neither standard mandates telemetry collection, API anomaly detection, or automated alerting mechanisms.
Threats such as token reuse, geographic drift in usage patterns, or unexpected HTTP method calls on sensitive endpoints often go undetected under these frameworks.
Why This Matters:
Unlike static systems, APIs can be probed continuously by attackers. Without automated detection capabilities, organizations can’t prevent or respond to fast-moving API attacks.
3. Inadequate Coverage of Integration-Specific Risk
🔍 The Gap:
API security risk is often a function of external dependencies—integrating third-party services, SDKs, or platforms into your environment. SOC 2 and ISO 27001 provide minimal guidance on evaluating the security posture of these dependencies.
SOC 2 may include vendor risk management as a control, but it does not assess whether third-party APIs expose excessive data, lack secure authentication, or follow OWASP API Security guidelines.
ISO 27001 requires risk assessments but allows organizations to self-define scope, which may exclude partner APIs or integrations altogether.
Implication:
A certified provider could integrate insecure APIs from a third party that bypass security controls entirely—yet remain compliant under both frameworks.
4. Point-in-Time Assessments vs. Continuous Security Assurance
🔍 The Gap:
Both standards rely on annual or periodic audits, which only capture a snapshot of an organization’s control effectiveness.
Vulnerabilities introduced after an audit period—such as insecure API deployments, changes to auth flows, or newly exposed endpoints—are not covered until the next audit.
There's no requirement for continuous validation, monitoring, or detection of real-time API threats.
Contrast With API Requirements:
API environments demand continuous testing (DAST, SAST, fuzzing) and runtime protection (RASP, gateway-level policies)—none of which are mandated or evaluated during SOC 2 or ISO 27001 certification.
5. Lack of Standardized Evaluation Criteria for API Security
🔍 The Gap:
Neither framework offers granular controls aligned with OWASP API Security Top 10, which has become the de facto industry standard for evaluating API-specific vulnerabilities.
SOC 2 and ISO 27001 do not require coverage or mitigation strategies for:
Broken Object-Level Authorization (BOLA)
Excessive data exposure
Mass assignment vulnerabilities
Insecure default configurations in APIs
Auditors typically do not validate API schemas, request/response filtering, or token scope enforcement during assessments.
Implication:
Organizations can remain compliant while exposing endpoints vulnerable to the most common and dangerous API attacks.
Rethinking Assurance for API-Driven Environments
While SOC 2 and ISO 27001 are important baseline frameworks, they were not designed to address the technical realities of modern, distributed, API-first architectures.
Organizations relying on third-party APIs—or exposing their own—must adopt supplemental evaluation frameworks, including:
OWASP API Security Top 10 compliance
Continuous security testing (DAST, fuzzing, schema validation)
Real-time monitoring and behavioral analytics
Runtime protection tools like API gateways and RASP
Threat intelligence enrichment for API-specific attack signatures
These additional controls provide ongoing visibility, resilience, and adaptability—all essential in an API-centric threat landscape that evolves faster than annual audit cycles can account for.
Why SOC 2 and ISO 27001 Aren’t Enough for API Security: Comparison and Decision Framework
As organizations increasingly build and scale API-first services or rely on third-party APIs to deliver core functionality, traditional security certifications like SOC 2 and ISO/IEC 27001 often provide a false sense of assurance.
While these certifications are important foundational signals of organizational maturity, they fall short in key technical areas that are essential to protecting APIs in real-world, modern environments.
APIs operate differently from traditional applications—they evolve quickly, they are exposed to the internet by default, and they are often integrated with external services or microservices ecosystems that bypass perimeter controls.
This requires granular, continuous, and API-specific security controls that are not addressed in legacy assurance frameworks.
To support security leaders, developers, GRC teams, and architecture decision-makers, we’ve created two critical resources:
A written comparison between SOC 2, ISO 27001, and the OWASP API Security Top 10
A decision support framework to help determine when additional API-specific security measures are needed beyond SOC 2 and ISO compliance
SOC 2 vs. ISO 27001 vs. OWASP API Security: What’s Missing?
SOC 2 focuses on trust criteria such as security, availability, confidentiality, and privacy—but it does so through the lens of broad controls and management processes.
It does not require direct evidence of how API endpoints are designed, tested, monitored, or protected in runtime environments.
ISO/IEC 27001 provides a formal structure for building an information security management system (ISMS), with emphasis on risk assessment, policy, and governance. While it includes high-level guidance on access control and software development practices, it does not mandate specific, technical API controls.
By contrast, the OWASP API Security Top 10 explicitly identifies common and critical vulnerabilities in APIs—including broken object-level authorization, excessive data exposure, and lack of rate limiting—and provides technical guidance on how to remediate them.
Neither SOC 2 nor ISO 27001 require organizations to:
Perform dynamic or runtime testing of APIs (such as fuzzing, DAST, or red teaming)
Implement or validate proper rate limiting, throttling, or abuse controls at the API level
Enforce granular access control and token scope management using standards like OAuth 2.0 or OpenID Connect
Monitor for token misuse or abnormal API activity, such as spikes from foreign geographies or repeated token replay attempts
Ensure compliance with API-specific security schemas (e.g., OpenAPI, Swagger) and endpoint classification
Validate security for public, internal, and partner-facing APIs individually
Detect and address undocumented (“shadow”) or deprecated APIs that may be exposed in production
If your API architecture relies heavily on integrations, microservices, or exposes sensitive data, relying solely on SOC 2 or ISO 27001 leaves gaps that can be exploited by attackers.
Decision Support Framework: When Do You Need More Than SOC 2 or ISO 27001?
To help guide GRC leaders, CISOs, and DevSecOps teams, here is a structured, plain-language framework to determine whether API-specific controls should be implemented in addition to SOC 2 and ISO 27001 compliance.
Step 1: Identify the Exposure
Ask:
Do we have public-facing APIs?
Are APIs used to transmit or process sensitive data (e.g., customer PII, financial data, healthcare records)?
Are these APIs accessed by third parties, mobile apps, or external platforms?
Are APIs deployed and updated frequently through CI/CD pipelines?
If the answer to any of these questions is “yes,” then static certifications are not enough—you need dynamic and contextual API protection.
Step 2: Understand Third-Party Integration Risk
Determine:
Are we relying on external APIs for core functionality like identity (SSO, OAuth), payment processing, or data enrichment?
Are we reviewing third-party API behavior or simply accepting vendor SOC 2 / ISO claims?
Do any of our vendors fail to provide API-specific penetration tests or security design documentation?
If you're integrating with third-party APIs without verifying their API security controls, your attack surface includes more than your own infrastructure.
Step 3: Assess Monitoring and Detection Readiness
Evaluate:
Can we detect real-time API anomalies (e.g., token replay, invalid auth attempts, abuse patterns)?
Do we use an API gateway or firewall with behavior-based analytics?
Is our SIEM or logging infrastructure integrated with API telemetry (methods, headers, geo-location, JWT claims)?
If monitoring is limited to system or network logs, you likely lack the visibility needed to respond to API-specific threats.
Step 4: Align Risk Level with Use Case
Map the risk of your APIs to business impact:
Public-facing or customer-facing APIs handling sensitive data require high-assurance controls
Internal APIs used for HR, finance, or regulatory functions may require mutual TLS, access scopes, and audit logging
APIs connected to third-party vendors should have explicit SLAs for response times, incident disclosure, and authentication standards
Step 5: Define and Implement API-Specific Security Measures
Based on your findings, implement:
API security testing tools (e.g., DAST, fuzzing, schema validation)
Real-time protection solutions (e.g., API gateways, runtime application self-protection)
OWASP API Security Top 10 alignment as an internal checklist
Threat modeling and data classification at the API route level
Contractual clauses with vendors that reflect authentication standards, response obligations, and audit rights
Key Takeaway
SOC 2 and ISO 27001 help you demonstrate foundational maturity, but in API-first environments, they cannot replace continuous, technical, and operational controls tailored to APIs.
The risks posed by API exposure—both your own and your vendors’—require a shift toward real-time protection, data-centric validation, and custom threat detection.
Incorporating OWASP API Top 10, schema enforcement, and runtime monitoring closes the gaps left by traditional certifications.
Overcoming Challenges of Dynamic API Security Evaluation
Implementing a dynamic and continuous security evaluation model for third-party APIs in SaaS environments offers significant advantages, but it also presents a set of complex operational, technical, and strategic challenges.
Below, we unpack these challenges and provide concrete recommendations and technical best practices to help organizations navigate them effectively.
1. Resource & Budget Constraints
🔍 The Challenge:
Continuous API security monitoring, testing, and compliance assurance demand a combination of specialized tools, skilled professionals, and ongoing financial investment.
For many organizations—particularly startups or those scaling quickly—budget and headcount limitations can slow or even prevent the adoption of robust security controls.
✅ How to Overcome:
a. Adopt Cost-Effective and Open-Source Security Tools
OWASP ZAP (Zed Attack Proxy): Use this dynamic application security testing (DAST) tool for automated scanning of public-facing APIs. ZAP supports scripting for custom test cases, making it ideal for DevSecOps integration.
Postman + Newman CLI: Automate security and functional API tests in CI/CD pipelines. Combine Postman with security-focused assertions to detect unusual API responses and headers.
Elastic Stack (Elasticsearch, Logstash, Kibana): Set up real-time log ingestion and visualization for API gateway traffic and anomalies, avoiding the cost of premium SIEM platforms.
b. Leverage Cloud-Native Security Features
Use AWS WAF, Google Cloud Armor, or Azure API Management to enable baseline API protections (rate limiting, IP blacklisting, injection pattern detection) without investing in third-party solutions.
c. Upskill Internal Security Staff
Encourage team certifications such as:
APIsec University – API Security Certification
SANS SEC588 (Cloud Pen Testing)
Certified API Security Professional (CAPISP)
Build internal knowledge-sharing programs and brown-bag sessions to distribute API security knowledge across DevOps, product, and security teams.
d. Use Vendor Consolidation
Choose platforms that integrate multiple security functions (e.g., Kong Konnect, Apigee X) to reduce licensing costs across DAST, monitoring, and authentication layers.
2. Alert Fatigue
🔍 The Challenge:
With continuous monitoring systems (API gateways, SIEMs, RASP, etc.), teams may encounter overwhelming volumes of alerts, many of which are false positives or low-severity events.
Alert fatigue causes desensitization, delayed responses, or missed critical threats.
✅ How to Overcome:
a. Prioritize Alerts Using MITRE ATT&CK Framework
Map API security logs (from anomaly detection or SIEM) to the MITRE ATT&CK for Enterprise matrix, especially categories like:
T1071.001 – Application Layer Protocol: Web Traffic
T1190 – Exploit Public-Facing Application
This mapping supports contextual triage, focusing analyst attention on alerts tied to known TTPs (Tactics, Techniques, Procedures).
b. Implement Threat Scoring and Correlation Algorithms
Enrich alerts using risk scoring models (e.g., based on user behavior, endpoint sensitivity, and historical activity) to elevate critical alerts.
Deploy correlation engines that link multiple low-level events (e.g., repeated failed token exchanges + unexpected IP + abnormal traffic volume) into a single prioritized incident.
c. Automate Tier-1 Response Tasks
Use Security Orchestration Automation and Response (SOAR) platforms like Tines, Cortex XSOAR, or Splunk SOAR to:
Auto-close false positives
Quarantine API tokens
Open tickets or Slack alerts for real anomalies
d. Customize Detection Rules
Fine-tune detection rules in SIEM and WAF platforms to reduce irrelevant logs. For instance, set geo-specific thresholds for API abuse, or suppress known safe IP ranges from noise-heavy alerts.
3. Integration Complexity
🔍 The Challenge:
Enterprise security ecosystems often involve multiple tools—API gateways, threat intelligence platforms, monitoring systems, compliance dashboards, and developer tools.
Getting these systems to communicate, coordinate, and scale together is a significant barrier.
✅ How to Overcome:
a. Standardize Around API-First Security Platforms
Choose platforms with robust, RESTful APIs and SDKs for integration:
API gateways like Kong, Tyk, or AWS API Gateway
SIEM platforms like Splunk or Microsoft Sentinel
Ticketing tools like Jira or ServiceNow
This allows for programmable workflows that automate enforcement, alerting, and remediation processes.
b. Use Middleware for Cross-System Communication
Implement message brokers (e.g., Apache Kafka, RabbitMQ) or integration services (e.g., Zapier, MuleSoft, Boomi) to sync API logs, health metrics, and policy violations across disparate systems.
c. Leverage Centralized Policy-as-Code
Use Open Policy Agent (OPA) or Rego to define and enforce consistent access policies across API endpoints and third-party integrations.
Integrate policy-as-code with CI/CD to apply access controls early in the deployment process.
d. Implement Unified Dashboards
Build a centralized security operations dashboard using tools like:
Grafana for visualization
Prometheus for metrics collection
Kibana for log analysis
These tools help create a unified visibility layer across your API security infrastructure.
e. Use CI/CD Security Plugins
Integrate tools like OWASP Dependency-Check, Snyk, and Checkmarx into your build pipeline to ensure that APIs deployed from third-party codebases are scanned for known vulnerabilities before deployment.
Final Thoughts on Challenge Mitigation
While the move to dynamic API security evaluation introduces several operational and technological hurdles, these can be mitigated through a combination of automation, strategic tooling, standardized integration approaches, and upskilling initiatives.
Organizations that effectively address these challenges can evolve from reactive compliance to proactive, intelligence-driven API security management—a must-have capability in today’s threat landscape.
Conclusion: Rewriting the Playbook for SaaS Third-Party Risk Management
API integrations are not just technical enablers—they’re potential security liabilities if not continuously monitored and validated. SOC 2 and ISO 27001 are no longer enough.
Security leaders must extend due diligence beyond static frameworks by embedding real-time, context-aware, and technically deep assessments into their third-party risk management processes.
A modern API security evaluation should include:
Continuous DAST/RASP testing
Real-time monitoring via gateways and SIEMs
SLA-driven incident response alignment
API-specific compliance and threat modeling
This evolution is not optional—it’s essential to securing SaaS at scale.
🔗 References:
OWASP API Security Top 10 – https://owasp.org/www-project-api-security/
NIST SP 800-204A: Building Secure Microservices-based Applications – https://csrc.nist.gov/publications/detail/sp/800-204a/final
Google Apigee API Security Guide – https://cloud.google.com/apigee/docs/api-platform/security
Gartner: “API Security – The Hidden Risk Behind Digital Transformation” – https://www.gartner.com/en/documents/3994790
CSA – Security Guidance for Critical Areas of Focus in Cloud Computing v4.0 – https://cloudsecurityalliance.org/artifacts/security-guidance-v4/
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