Pentest Letter of Attestation Sample: 8 Templates for MSPs [2026]

For Managed Service Providers (MSPs), vCISOs, and GRC firms, proving security work is complete and effective is a constant challenge. You perform a critical penetration test or vulnerability scan for a client, but how do you formally document it for their auditors or compliance needs? The answer is a letter of attestation. This formal document serves as official proof, connecting a technical penetration testing report to the verifiable evidence needed for compliance frameworks like SOC 2, HIPAA, and PCI DSS.

This article is your go-to resource for creating these essential documents. We provide several editable letter of attestation sample templates tailored for our partners' specific needs. As a channel-only pentesting provider, we never compete with you; our goal is to empower your business. We solve common industry problems like inflated prices and long lead times with affordable, fast, and manual pentesting services from certified experts (OSCP, CEH, CREST).

You'll find eight templates with detailed breakdowns, covering everything from a standard pen test completion attestation to specific documents for SOC 2 evidence and white label pentesting scenarios. This is a practical toolkit for proving your value, building client trust, and satisfying auditors.

Penetration Test Completion Attestation Letter

A Penetration Testing Completion Attestation Letter is a formal document from certified security professionals after a penetration test. It proves that your organization conducted a security assessment. This letter confirms a penetration testing engagement was performed according to the agreed-upon scope and timeline. It's a high-level summary, not the full, detailed report.

For an MSP, this document is critical. It lets you give clients and auditors verification that a pen test was completed by qualified experts, such as those with OSCP or CREST certifications. It's the perfect executive-level document to share without revealing sensitive vulnerability data, making it an essential letter of attestation sample for any security-conscious provider.

When to Use This Pen Test Attestation

This letter is essential in several common business scenarios for MSPs and vCISOs. Use it for SOC 2 compliance when auditors request proof of annual penetration testing. Financial services and public companies often need it for regulatory filings. Healthcare organizations use it to document their risk assessment activities for HIPAA compliance. Your clients might also ask for it to satisfy their own internal security policies.

How to Implement This Attestation Letter

To make your attestation effective, focus on clarity and professionalism. Include key details like the testing dates, the scope (e.g., specific IP ranges), and the testers' credentials (like OSCP or CEH). Reference the full penetration test report but do not include findings. If you are a white label reseller, ensure the letter is on your MSP or vCISO letterhead to maintain brand consistency for your client. The letter should attest to the work performed, not make guarantees about security.

Vulnerability Assessment Attestation Letter

A Vulnerability Assessment Attestation Letter confirms a comprehensive vulnerability assessment was performed. It documents the scope of systems tested, the tools used, and the approach taken to find security weaknesses. This letter is different from a penetration test attestation because it focuses on finding vulnerabilities, not actively exploiting them.

For MSPs and vCISOs, this letter proves a client's environment was systematically scanned for known security issues. It attests that the vulnerability assessment was completed by qualified professionals. This document is a critical letter of attestation sample for showing due diligence in security monitoring without disclosing specific vulnerability details.

When to Use This Assessment Attestation

This letter is crucial for documenting routine security hygiene and meeting compliance requirements. Use it for quarterly security reviews required by frameworks like PCI DSS. It also verifies that AWS or Azure environments have been assessed for misconfigurations and known vulnerabilities. You can also supply this to partners to prove your SaaS applications have undergone security checks or issue it after major system updates.

How to Implement a Vulnerability Attestation

To make this attestation clear, focus on methodology and scope. Clearly state whether the assessment involved automated scanning, manual pentesting review, or a combination. Name the specific scanning tools and vulnerability databases referenced. Briefly mention that a process was in place to review findings, which adds credibility. Include the exact date range of the assessment to show it is a current snapshot of the system's security state.

Red Team Exercise Attestation Letter

A Red Team Exercise Attestation Letter documents the completion of an advanced, objective-driven adversarial attack simulation. It serves as formal proof that an organization’s defenses were tested against real-world attack scenarios. This letter confirms that a red team engagement was performed, detailing the high-level objectives and timeframe without revealing sensitive tactics or procedures.

For MSPs and vCISOs supporting mature clients, this document is invaluable. It validates a proactive and advanced security posture to executives and regulators. Unlike a standard pen test, a red team exercise is broader and more complex. This attestation provides a concise summary for stakeholders, making it a critical letter of attestation sample for demonstrating top-tier security validation. For more on these assessments, see our guide on the penetration test and vulnerability assessment.

When to Use a Red Team Attestation

This letter is ideal for organizations proving they go beyond standard compliance checks. It shows the board that defenses are actively tested against sophisticated threats. Financial institutions and government contractors use this to prove their resilience. It also provides evidence that the Security Operations Center (SOC) and incident response teams were tested under realistic conditions.

How to Implement a Red Team Letter

To maximize the impact of your red team attestation, precision is key. Clearly state that the exercise was conducted under strict, pre-approved Rules of Engagement (ROE). Mention the overall goals, like "to test incident response capabilities," without detailing specific attack paths. Include the start and end dates of the engagement. The letter must attest to the exercise's completion while protecting the specific TTPs used by the red team.

Social Engineering Testing Attestation Letter

A Social Engineering Testing Attestation Letter confirms an organization has undergone a security assessment focused on human vulnerabilities. This letter is high-level proof that activities like phishing campaigns were conducted by security experts. It validates that the testing was performed within an agreed-upon scope and ethical framework, without disclosing individual employee performance.

For MSPs and vCISOs, this attestation is a powerful tool to demonstrate a mature security program. It proves to clients and auditors that you are proactively evaluating the "human firewall." Sharing this letter of attestation sample verifies a social engineering engagement occurred, helping clients satisfy compliance without exposing raw test data.

When to Use a Social Engineering Attestation

This letter is crucial for documenting security awareness. For PCI DSS compliance, Requirement 12.6 mandates a formal security awareness program, and this letter provides evidence. For ISO 27001, it helps demonstrate that security training is being tested. Banks and financial firms use it to prove they are testing employee susceptibility to fraud. Cybersecurity insurers often require proof of security awareness training and testing.

How to Implement This Attestation Letter

For a valuable social engineering attestation, be clear and sensitive. State that the engagement was fully authorized by management. Detail the types of social engineering performed and the campaign dates. Include high-level, anonymous statistics, such as the percentage of recipients who clicked a phishing link. Suggest that the detailed report includes recommendations for security awareness training.

SOC2 Compliance Attestation Letter

A SOC2 Compliance Attestation Letter is direct evidence for auditors that required security testing has been completed. This letter confirms your organization performed penetration testing and vulnerability assessments aligned with the SOC 2 framework. It's a formal declaration that your testing methodologies meet the standards auditors expect.

For MSPs and vCISOs helping clients achieve or maintain SOC 2 compliance, this letter is essential. It connects the technical pen test report to the auditor's need for a simple confirmation. This letter of attestation sample provides the exact proof auditors need, confirming testing activities were properly scoped to support a client's SOC 2 Type II report.

When to Use This SOC2 Attestation

This letter is crucial for organizations undergoing SOC 2 audits. It is essential for any SaaS company seeking an annual SOC 2 Type II report. Cloud service providers use it to give their own customers the documentation needed for their compliance efforts. It is also required by fintech platforms to demonstrate robust security controls to clients and regulators.

How to Implement a SOC2 Attestation Letter

To ensure your SOC 2 attestation is effective, be precise. Ensure the testing dates on the letter fall within the SOC 2 audit period. Mention the specific SOC 2 Common Criteria controls that the penetration testing helps address. Proactively share your testing methodology with the external auditors to get their buy-in before the engagement begins. This prevents last-minute issues.

Mobile Application Security Attestation Letter

A Mobile Application Security Testing Attestation Letter confirms a comprehensive security assessment was performed on a mobile app. This letter is formal proof that the app underwent a rigorous pen test covering mobile-specific attack vectors. It verifies that experts tested the app's local data storage, API security, and other platform-specific vulnerabilities for both iOS and Android.

For MSPs and vCISOs supporting clients with mobile apps, this letter of attestation sample is indispensable. It allows you to assure stakeholders that the mobile application was properly vetted by qualified security professionals. The letter provides a high-level summary suitable for executive review or compliance audits, without exposing all security findings.

When to Use a Mobile App Attestation

This specialized letter is vital for several mobile-centric scenarios. Use it to document due diligence for privacy regulations before launching on app stores. Financial and healthcare providers need this to certify that their apps meet strict security standards. For SOC 2 and HIPAA compliance, auditors often require it as evidence of a risk assessment for mobile components. Understanding different compliance frameworks is key; a deep dive into SOC vs SOX Navigating Compliance can clarify why this documentation is necessary.

How to Implement a Mobile App Attestation

To make your mobile attestation impactful, be precise. Clearly state the exact application versions tested. Structure the attestation to address iOS and Android testing independently. Include a statement confirming that the associated API backend was part of the penetration testing scope. Mention that the pen test was based on a threat model specific to mobile, like the OWASP Mobile Application Security Verification Standard (MASVS).

External Network and Infrastructure Attestation Letter

An External Network and Infrastructure Attestation Letter verifies that a security assessment of an organization’s internet-facing systems is complete. This letter is high-level proof that a comprehensive penetration testing engagement was conducted on the external attack surface. It confirms the scope and completion of the assessment without disclosing specific vulnerabilities.

This attestation is a key asset for demonstrating due diligence. For MSPs and vCISOs, it provides clients with tangible evidence of external security validation. It acts as an authoritative summary of a completed pen test, confirming that experts have examined the systems exposed to the internet. This makes it a crucial letter of attestation sample for proving proactive security measures.

When to Use an External Network Attestation

This letter is vital for documenting the security of your public assets. Provide this letter to clients to satisfy their vendor management requirements. Use it as evidence for PCI DSS Requirement 11.3, which mandates regular external penetration testing. After a security incident, this attestation can help show that controls have been hardened. Assure investors and stakeholders that the organization is actively managing its external security risk.

How to Implement an External Network Attestation

To maximize impact, focus on precision. Explicitly list the types of systems tested, such as SaaS platforms, firewalls, and cloud infrastructure. Before testing, notify any relevant third parties like ISPs and cloud providers. Mention that the assessment included correlating findings from sources like SHODAN. The letter attests that a penetration test was performed; it is not a guarantee of future security.

Cloud Infrastructure Security Attestation Letter

A Cloud Infrastructure Security Attestation Letter confirms a thorough security assessment of a cloud environment like AWS, Azure, or Google Cloud. This letter verifies that an organization’s cloud systems have been subjected to a detailed penetration test. It summarizes the evaluation of key areas such as cloud configuration, Identity and Access Management (IAM), and data protection. It is a high-level summary for stakeholders.

This document is essential for any business operating in the cloud. It provides clients, auditors, and partners with proof that a pen test of the cloud infrastructure was performed by qualified experts. It’s the perfect executive-level document to share without exposing sensitive configuration details, making it a critical letter of attestation sample for MSPs managing client cloud environments.

When to Use a Cloud Infrastructure Attestation

This letter is crucial for validating the security posture of cloud-native systems. After migrating to the cloud, use this to assure stakeholders the new environment is secure. When using multiple cloud providers, it documents a consistent security baseline. For containerized workloads, it attests that Kubernetes clusters have been assessed. Provide this to clients to prove your managed cloud services meet their security requirements for SOC 2 or ISO 27001.

How to Implement a Cloud Attestation Letter

To make your cloud attestation impactful, focus on specifics. Mention that testing was aligned with Infrastructure-as-Code (IaC) deployment cycles. Clearly state the scope, including the cloud provider and specific services tested. Allude to testing methodologies aligned with frameworks like the MITRE ATT&CK for Cloud or CIS Benchmarks. Note that the assessment included checks for common cloud misconfigurations, without revealing the results.

Partner with Us for Your Pentesting Needs

Throughout this guide, we have explored the critical role a letter of attestation sample plays in cybersecurity and compliance. From demonstrating the completion of a rigorous penetration test to verifying evidence for a SOC 2 audit, these documents are more than a formality. They are powerful tools that build trust, satisfy regulatory requirements, and protect your clients.

Mastering the attestation letter transforms it from an administrative task into a strategic asset. A well-crafted letter provides undeniable proof of due diligence and highlights the value of your security services. For MSPs, vCISOs, and GRC professionals, the ability to produce these documents is a core competency. Your clients rely on you not just for the technical execution of a pen test but also for the official documentation that helps them achieve their business goals.

This is where a true channel-only partnership becomes essential. The managed service industry has a problem with inflated prices, bad testing methodology, and long lead times. We are the solution. We are a channel-only partner providing affordable, manual pentesting conducted by certified professionals (OSCP, CEH, and CREST).

We give you the tools to succeed, including comprehensive reports and professionally formatted attestation letters, all designed to be white-labeled. You maintain the client relationship while we handle the complex security testing. Our focus on white-label pentesting means we never compete with you. We are 100% channel-only, dedicated to helping your MSP or vCISO practice grow and meet client compliance needs for frameworks like PCI DSS and ISO 27001. You bring the client; we bring the certified expertise.

Ready to offer expert penetration testing services to your clients without the overhead? We provide the channel-only, white label pentesting solution you need. Contact us to see how you can get a complete pentest report and a professional letter of attestation sample delivered in under a week.