SaaS Security Due Diligence Checklist

Your vendor risk assessments are taking too long because you're rebuilding the wheel for every SaaS evaluation. A properly structured SaaS Security Due Diligence Checklist transforms ad-hoc questionnaires into repeatable, defensible assessments that capture the right evidence the first time.

SaaS vendors now comprise the majority of the average enterprise technology stack, yet most organizations still assess them using generic IT questionnaires that miss cloud-specific risks. Authentication federation, data residency, API security, multi-tenancy isolation — these critical SaaS controls require targeted questions that general DDQs don't address.

This checklist serves as your master template for evaluating any SaaS vendor, from critical payment processors to low-risk marketing tools. It provides the question bank, scoring methodology, and control mappings needed to execute consistent, thorough assessments that satisfy both internal governance requirements and external audit expectations.

Core Components of the SaaS Security Due Diligence Checklist

1. Authentication and Access Control (25-30 questions)

Focus on SSO capabilities, MFA enforcement, privileged access management, and session controls. Critical questions include:

• SAML/OAuth implementation details
• Password policy enforcement mechanisms
• Service account management procedures
• Session timeout configurations
• Role-based access control granularity

Scoring weight: 15-a meaningful portion of total risk score for critical vendors.

2. Data Protection and Encryption (30-35 questions)

Evaluate encryption at rest, in transit, and in processing. Key areas:

• Encryption algorithms and key management
• Data classification capabilities
• DLP implementation
• Tokenization/masking options
• Customer-managed encryption keys (CMEK)

Red flags: Proprietary encryption, shared encryption keys, no key rotation policy.

3. Infrastructure Security (20-25 questions)

Assess the underlying cloud architecture and security controls:

• Cloud provider details (AWS, Azure, GCP)
• Network segmentation approach
• Vulnerability management cadence
• Patch management SLAs
• Container/serverless security measures

4. Incident Response and Business Continuity (15-20 questions)

Validate operational resilience:

• Incident notification timelines
• RTO/RPO commitments
• Backup frequency and testing
• Disaster recovery site details
• Customer data portability options

Industry-Specific Applications

Financial Services

Additional focus areas for banks, insurance, and fintech:

• Regulatory reporting: SOX compliance evidence, GLBA safeguards
• Transaction monitoring: Real-time fraud detection capabilities
• Audit trails: Immutable logs for financial transactions
• Geographic restrictions: Data residency for specific jurisdictions

Control mappings: FFIEC CAT, PCI DSS, NYDFS 23 NYCRR 500

Healthcare

HIPAA-aligned additions:

• PHI handling: Encryption standards for protected health information
• Access controls: Break-glass procedures, minimum necessary access
• Audit logging: 6-year retention for access logs
• Business Associate Agreement: Liability terms, breach notification

Control mappings: HIPAA Security Rule, HITRUST CSF

Technology/B2B SaaS

Developer-focused controls:

• API security: Rate limiting, authentication methods, versioning
• Development practices: SSDLC, code review processes, dependency management
• Integration security: Webhook validation, OAuth scope management
• Performance monitoring: SLA tracking, latency commitments

Compliance Framework Alignment

SOC 2 Trust Services Criteria Mapping

The checklist directly maps to all five TSCs:

1. Security (CC): most questions
2. Availability (A): a notable share of questions
3. Confidentiality (C): a meaningful portion of questions
4. Processing Integrity (PI): some questions
5. Privacy (P): a notable share of questions

Each question includes TSC reference codes for evidence organization.

ISO 27001:2022 Control Mapping

Covers all 93 controls across:

• A.5: Organizational controls
• A.6: People controls
• A.7: Physical controls
• A.8: Technological controls

Questions include specific control references (e.g., A.8.24 for cryptography).

GDPR Articles 25 and 32

Technical and organizational measures assessment:

• Privacy by design implementation
• Data minimization practices
• Purpose limitation controls
• Consent management mechanisms
• Cross-border transfer safeguards

Implementation Best Practices

1. Risk-Based Tiering

Apply different checklist depths based on vendor criticality:

Tier	Data Classification	User Count	Checklist Sections
Critical	Restricted/Confidential	>1000	All 12 sections
High	Internal Use	100-1000	8-10 sections
Medium	Public	10-100	5-7 sections
Low	Public	<10	3-4 sections

2. Response Validation

Don't accept vendor attestations at face value. Request:

• Policy documents for claimed controls
• Architecture diagrams for infrastructure questions
• Audit reports (SOC 2, ISO certificates)
• Penetration test summaries
• Sample logs or screenshots

3. Continuous Monitoring Integration

Initial assessments are just the start. Build in:

• Quarterly control attestations for critical vendors
• Annual reassessment triggers
• Certificate expiration tracking
• Breach notification monitoring
• Performance metric reviews

Common Implementation Mistakes

1. One-Size-Fits-All Approach

Sending the full 200+ question checklist to every vendor wastes time and damages relationships. Low-risk marketing tools don't need the same scrutiny as your core banking platform.

2. Accepting Vague Responses

"We follow industry best practices" isn't an answer. Demand specifics: encryption algorithms, backup frequencies, incident response timelines.

3. Ignoring Operational Controls

Security teams often focus exclusively on technical controls while missing critical operational risks: financial stability, insurance coverage, subcontractor management.

4. Manual Scoring Calculations

Spreadsheet formulas break. Build scoring logic into your GRC platform or use automated calculation tools to ensure consistent risk ratings.

5. Forgetting Legal Review

Technical assessments must align with contract terms. Involve legal early to ensure SLAs, liability caps, and indemnification clauses match your risk tolerance.

Frequently Asked Questions

How long should vendors have to complete the SaaS security checklist?

Standard timeline is 2-3 weeks for critical vendors, 1-2 weeks for others. Build buffer time into your procurement process and provide the checklist during initial vendor discussions.

Should we customize the checklist for each vendor or keep it standardized?

Use a modular approach: maintain a standard core (60-70%) with industry and criticality-specific modules (30-40%). This balances consistency with relevance.

How do we handle vendors who refuse to complete our checklist?

Escalate to procurement and legal teams. For critical vendors, non-completion should be a deal-breaker. For others, accept alternative evidence like SOC 2 reports or completed SIG questionnaires, then map responses to your controls.

What's the difference between a security questionnaire and a due diligence checklist?

Questionnaires gather information; checklists drive decisions. Your checklist should include scoring criteria, control mappings, and clear pass/fail thresholds for each assessment area.

How often should we update our SaaS due diligence checklist?

Review quarterly, update annually. Add questions based on emerging threats, remove outdated controls, and adjust scoring weights based on incident data.

Can we use the same checklist for on-premise and SaaS vendors?

No. SaaS assessments require cloud-specific controls around multi-tenancy, API security, and shared responsibility models that don't apply to on-premise software.