What is Penetration Testing

Third-party penetration testing reports rank among the most valuable artifacts in vendor due diligence. Unlike questionnaires or attestations, penetration tests reveal how security controls perform under actual attack conditions. For GRC analysts managing vendor portfolios, these reports provide quantifiable risk data that directly feeds control mapping exercises and audit preparations.

The challenge lies in interpretation. A penetration test report showing 15 high-severity findings doesn't automatically disqualify a vendor—context determines impact. The vendor's remediation timeline, compensating controls, and your organization's risk appetite all factor into the assessment. This guide breaks down penetration testing requirements across major frameworks, explains how to incorporate findings into vendor scorecards, and provides practical templates for requesting and evaluating vendor penetration test reports.

Technical Definition and Scope

Penetration testing systematically probes networks, applications, and systems using the same tools and techniques as malicious actors. Unlike vulnerability scanning, which identifies potential weaknesses, penetration testing exploits these vulnerabilities to demonstrate actual impact. Testers chain multiple vulnerabilities together, pivot between systems, and attempt privilege escalation—mirroring real attack patterns.

In vendor risk contexts, penetration tests validate the effectiveness of security controls documented in questionnaires and compliance certificates. A vendor might claim they enforce network segmentation, but penetration testing proves whether an attacker can actually move laterally between segments.

Regulatory Requirements and Framework Alignment

SOC 2 Requirements

SOC 2 Type II reports increasingly include penetration testing results under CC4.1 (COSO Principle 16). While not explicitly mandated, auditors expect annual penetration tests for Trust Services Criteria compliance. The test scope must cover:

• Systems processing customer data
• Administrative interfaces
• API endpoints exposed to clients
• Network perimeter controls

ISO 27001:2022 Mapping

Control A.8.8 explicitly requires "technical security testing." Most ISO auditors interpret this as penetration testing for internet-facing systems. The testing frequency depends on:

• Risk assessment outcomes (Clause 6.1.2)
• Previous test findings
• System criticality ratings
• Change velocity

PCI-DSS v4.0 Specifications

Requirement 11.4 mandates penetration testing:

• Annual testing minimum
• After significant infrastructure changes
• Covers CDE (Cardholder Data Environment) and adjacent systems
• Must include social engineering components
• Requires qualified internal or external testers

GDPR Article 32 Implications

While GDPR doesn't explicitly require penetration testing, Article 32(1)(d) mandates "regularly testing, assessing and evaluating the effectiveness of technical measures." DPAs (Data Protection Authorities) consistently cite penetration testing as evidence of compliance during investigations.

Vendor Assessment Integration

Pre-Contract Due Diligence

Request penetration test executive summaries during vendor evaluation. Key elements to verify:

Test Scope Coverage

• Production systems handling your data
• Development environments with production access
• Third-party integrations
• Cloud infrastructure components

Methodology Standards

• OWASP Testing Guide for web applications
• PTES (Penetration Testing Execution Standard)
• NIST SP 800-115 for network testing
• Cloud-specific frameworks (CSA CCM)

Tester Qualifications

• OSCP, GPEN, or equivalent certifications
• Independence from development teams
• Specialized expertise matching tested systems

Ongoing Monitoring Requirements

Structure penetration testing requirements in vendor contracts:

Vendor Criticality	Testing Frequency	Report Requirements	Remediation SLA
Critical	Quarterly	Full report + remediation evidence	30 days for high/critical
High	Semi-annual	Executive summary + technical details	60 days for high/critical
Medium	Annual	Executive summary	90 days for high/critical
Low	Upon request	Attestation letter	Best effort

Control Effectiveness Validation

Map penetration test findings to your control framework:

1. Authentication Controls: Password spray success rates, MFA bypass attempts
2. Network Segmentation: Lateral movement paths discovered
3. Data Protection: Sensitive data exposure through SQL injection or API abuse
4. Patch Management: Exploitation of known vulnerabilities with available patches
5. Incident Response: Time to detect and respond to tester activities

Common Vendor Pushback and Responses

"We have SOC 2, that's sufficient" SOC 2 focuses on control design and operating effectiveness, not technical exploitation. Penetration testing validates whether those controls actually prevent attacks.

"Our WAF blocks all attacks" WAFs provide one layer of defense. Penetration testing reveals bypass techniques, logic flaws, and authentication weaknesses that WAFs cannot address.

"Testing causes downtime" Professional penetration testing includes rules of engagement preventing service disruption. Most testing occurs in parallel environments or uses rate-limiting to avoid impact.

"It's too expensive for our size" Risk-based scoping reduces costs. Start with external attack surface testing ($5-15K) before comprehensive assessments. Many vendors already test for their own needs—you're requesting report sharing, not additional testing.

Industry-Specific Considerations

Financial Services

FFIEC guidance expects penetration testing for online banking systems. Tests must include:

• ATM networks and interfaces
• Wire transfer systems
• Mobile banking applications
• Third-party payment processor connections

Healthcare

HIPAA Security Rule 164.308(a)(8) requires "periodic technical and nontechnical evaluation." Healthcare vendors should test:

• EHR system interfaces
• Medical device networks
• Patient portal applications
• HIE (Health Information Exchange) connections

Technology/SaaS

B2B SaaS vendors typically need:

• Multi-tenant isolation testing
• API security assessment
• CI/CD pipeline evaluation
• Container and orchestration platform testing

Practical Implementation Guide

Requesting Reports

Use this template for vendor communications:

Per our security requirements, please provide your most recent penetration test report including:
- Executive summary with scope and methodology
- Critical and high findings with evidence
- Remediation status for all findings
- Tester qualifications and independence attestation
- Testing date (must be within 12 months)

If full reports cannot be shared, please provide:
- Sanitized findings summary
- Letter of attestation from testing firm
- Remediation evidence for critical/high findings

Evaluating Results

Create a scoring matrix for consistent assessment:

1. Finding Severity Distribution (40% weight)

   • 0 critical/high = 100 points
   • 1-3 critical/high = 75 points
   • 4-10 critical/high = 50 points

   • 10 critical/high = 0 points

2. Remediation Timeline (30% weight)

   • Fixed within SLA = 100 points
   • Fixed outside SLA = 50 points
   • Not fixed = 0 points

3. Testing Comprehensiveness (30% weight)

   • Full scope = 100 points
   • Partial scope = 50 points
   • Limited scope = 25 points

Continuous Monitoring

Integrate penetration test findings into your GRC platform:

• Create findings as risks with vendor ownership
• Track remediation through exception management workflows
• Update vendor risk scores based on test results
• Generate audit trails for regulatory examinations
• Schedule follow-up validation testing

Frequently Asked Questions

How do I verify a penetration testing firm's credibility when reviewing vendor reports?

Check for CREST, PCI ASV, or regional certifications. Review sample reports for MITRE ATT&CK mapping, clear reproduction steps, and business impact analysis. Qualified firms provide CVE references, exploit code snippets, and risk ratings aligned with CVSS or similar frameworks.

What's the minimum acceptable frequency for vendor penetration testing?

Annual testing is the regulatory baseline across SOC 2, ISO 27001, and PCI-DSS. Increase to semi-annual for critical vendors processing sensitive data or those with internet-facing applications. Quarterly testing applies to payment processors, critical infrastructure, or vendors with poor security track records.

Should I require black box, gray box, or white box testing from vendors?

Gray box testing provides the best balance for vendor assessments. Testers receive basic architecture information and user accounts, simulating insider threats while maintaining efficiency. Black box testing misses many issues; white box testing might not reflect real-world attack scenarios.

How do I handle vendors who refuse to share penetration test reports?

Escalate through procurement with specific regulatory citations. Accept attestation letters from testing firms as a compromise, but increase other compensating controls like security questionnaires, insurance reviews, and contract liability terms. Document the refusal in your risk register.

What's the difference between penetration testing and red teaming?

Penetration testing follows a defined scope with specific targets and timeframes. Red teaming simulates advanced persistent threats with broader objectives, often including physical security and social engineering. Most vendor assessments need penetration testing; red teaming applies to critical infrastructure vendors.

Can I rely on bug bounty programs instead of penetration testing?

Bug bounties complement but don't replace penetration testing. Bounty programs provide continuous coverage but lack comprehensive methodology, miss business logic flaws, and don't test internal systems. Require both for critical vendors; accept either for medium-risk vendors.

How do I map penetration test findings to my control framework for audit evidence?

Create a findings-to-controls matrix. SQL injection maps to input validation controls. Privilege escalation maps to access control. Each finding should trace to specific control numbers in your framework (ISO 27001, NIST CSF, etc.) with severity ratings affecting control effectiveness scores.

What remediation timeline should I expect for critical penetration test findings?

Industry standard: 30 days for critical, 90 days for high, 180 days for medium. Adjust based on complexity—infrastructure changes take longer than application patches. Require compensating controls for any delays. Get written remediation plans with milestone dates for tracking.