ELI5: What is an External Audit?
It’s like having a referee from outside your school come check that everything is fair. An external auditor is an independent outsider who inspects a company’s security, which makes the results more trustworthy.
Definition
An external audit is an assessment performed by an independent third-party auditor who has no organizational affiliation with the entity being audited. External audits provide objective assurance to customers, regulators, and other stakeholders because the auditor has no conflict of interest. External audits are required for major certifications (ISO 27001, SOC 2) and regulatory compliance attestations (PCI DSS QSA assessment, HIPAA OCR investigations).
Key Details
- Independence is the key differentiator: external auditors have no stake in the outcome and bring unbiased judgment
- Required for certifications: ISO 27001 certification requires an accredited external certification body
- PCI DSS Level 1 merchants must undergo an annual Report on Compliance (ROC) by a Qualified Security Assessor (QSA)
- SOC 2 reports are issued by independent CPA firms following SSAE 18 standards
- Exam tip: external audits provide the highest level of assurance; internal audits provide ongoing monitoring but lower assurance to external parties
Connections
- Parent: audits-and-assessments — external audits are the most authoritative form of audit assurance
- See also: internal-audit
- See also: soc-reports