External Audit
Definition
An external audit is an independent assessment conducted by a qualified third-party auditor, certification body, or assessment organization to formally evaluate an organization's compliance with specific standards, regulations, or frameworks. The result is a formal report, certification, or attestation that provides assurance to stakeholders.
Types of External Auditors
CPA Firm (SOC 2)
Licensed CPA firms conduct SOC 2 examinations following AICPA standards. They issue SOC 2 Type I or Type II reports attesting to control design and effectiveness.
Certification Body (ISO 27001)
Accredited certification bodies conduct Stage 1 and Stage 2 audits to award ISO 27001 certification, followed by annual surveillance audits.
QSA (PCI-DSS)
Qualified Security Assessors are certified by the PCI Security Standards Council to validate compliance with PCI-DSS requirements.
C3PAO (CMMC)
Certified Third-Party Assessment Organizations are authorized by the CMMC Accreditation Body to conduct formal CMMC assessments.
OCR (HIPAA)
The Office for Civil Rights within HHS conducts HIPAA compliance reviews and investigations, though most HIPAA audits are conducted by contracted assessors.
What to Expect During an External Audit
Opening meeting to confirm scope, timeline, and logistics
Evidence requests -- auditors will ask for specific documentation and system artifacts
Personnel interviews -- key staff will be questioned about their roles and processes
Technical testing -- auditors may verify configurations, run vulnerability scans, or review code
Daily status updates to communicate progress and preliminary observations
Closing meeting to discuss findings, observations, and next steps
Formal report delivery with opinion, findings, and recommendations