When a VPN provider announces it has “passed an independent security audit,” the phrase does a lot of work while explaining very little. Different auditing firms specialize in different kinds of testing, use different methodologies, and produce reports with very different levels of detail. Understanding how these firms actually operate — rather than treating “audited” as a single uniform badge — is essential to interpreting what a given claim really means.
Two Broad Categories of VPN Audits
Most VPN-related security engagements fall into one of two broad categories, and conflating them is one of the most common mistakes readers make when evaluating a provider’s claims.
Penetration Testing and Application Security Audits
These engagements focus on finding exploitable vulnerabilities: insecure API endpoints, authentication weaknesses, cryptographic implementation flaws, or client-side bugs in desktop and mobile applications. Firms specializing in offensive security testing typically produce a technical vulnerability report listing each discovered issue with a severity rating (critical, high, medium, low, informational) alongside proof-of-concept details and remediation guidance.
No-Logs and Privacy Practice Assessments
These are a fundamentally different kind of engagement. Rather than hunting for exploitable bugs, the auditor reviews infrastructure configuration, internal processes, and data handling practices to assess whether the provider’s stated privacy policy matches its actual technical practice. This work more closely resembles a compliance or process audit than a penetration test, and it is usually conducted by accounting or assurance-focused firms rather than pure offensive-security shops.
A provider that has undergone one type of audit but not the other has only had part of its story verified. A clean penetration test says nothing about logging practices, and a clean no-logs assessment says nothing about whether the app itself is riddled with exploitable bugs.
How a Typical Engagement Is Structured
Regardless of specialty, most credible audit engagements follow a broadly similar arc:
- Scoping call — the provider and auditor agree on what systems, applications, or policies are in scope, and what is explicitly excluded.
- Access provisioning — the provider grants the auditor whatever access is needed: source code repositories, staging or production server access, architecture diagrams, or interview time with engineering staff.
- Active testing period — this is the bulk of the engagement, typically lasting one to four weeks depending on scope, during which the auditor runs automated scans, manual code review, configuration checks, and targeted testing of specific components.
- Draft findings and remediation window — the auditor shares preliminary findings with the provider, who then has an opportunity to fix identified issues before the final report is published.
- Final report — a complete document is issued, sometimes with a public-facing summary and a more detailed technical annex shared only with the provider.
The remediation window is worth paying attention to specifically. A published report that shows issues found and subsequently fixed, with a verification step confirming the fix, is generally more meaningful than a report showing zero findings at all — a completely clean bill of health on a first-time engagement can sometimes indicate a narrower scope rather than a genuinely flawless system.
What Separates a Strong Engagement From a Weak One
Because “we were audited” has become a marketing checkbox across the VPN industry, it’s useful to have concrete criteria for judging engagement quality rather than relying on the headline claim alone.
Scope Breadth
Did the audit cover the core VPN protocol implementation, the desktop and mobile client applications, the account and billing systems, and the browser extensions — or just one of these? Providers with multiple products sometimes advertise a single audit of one component as though it validates the entire platform.
Access Depth
Was the auditor given full source code and production access, or only a limited, provider-curated view? Reports that specify “white-box” access (full visibility) carry more weight than engagements conducted under heavy restriction.
Report Transparency
Is the full report, including specific findings, available publicly, or does the provider only publish a marketing summary referencing the audit without technical substance?
Recency and Repetition
Has the engagement been repeated on a regular cadence, or does the provider still reference a single audit from several product versions ago?
Reading Severity Ratings Correctly
Vulnerability findings in penetration test reports are usually categorized by severity, and readers unfamiliar with this convention sometimes over- or under-react to the presence of findings. A report listing several low or informational findings is not necessarily worse than a report with zero findings — it may simply reflect a more thorough testing process. What matters most is whether any critical or high-severity findings were left unresolved at the time of publication, and whether the provider’s response demonstrates a functioning remediation process rather than defensiveness or delay.
The presence of findings in an audit report is not itself a red flag. The absence of any remediation process for those findings is.
Interview-Based Assessments and Their Value
Alongside technical testing, many privacy-practice audits include structured interviews with engineering, legal, and operations staff. These interviews serve a purpose that pure technical review cannot: they surface informal practices, ad hoc tooling, or undocumented exceptions that wouldn’t necessarily show up in a code review. A support ticketing system that inadvertently retains IP addresses attached to customer complaints, for example, is exactly the kind of gap that interview-based review is designed to catch, and it’s a common finding across the industry.
Questions to Ask When a Provider Cites an Audit
- Which specific systems were in scope — core infrastructure, apps, billing, or all three?
- Was this a penetration test, a no-logs assessment, or both?
- Is the full technical report published, or only a summary?
- What access level did the auditor have — white-box, gray-box, or black-box?
- Has the engagement been repeated since the version being tested was current?
Walking Through a Combined Engagement
To make these categories concrete, consider how a well-run combined engagement typically unfolds when a provider commissions both a penetration test and a no-logs assessment in the same cycle. The penetration testing team usually works from the client applications inward — attempting to intercept or manipulate traffic between the app and the VPN server, probing the authentication API for logic flaws, and reviewing the cryptographic handshake implementation against current best practices. In parallel, the privacy-practice assessment team works from the infrastructure outward — reviewing server provisioning scripts, checking whether any per-user identifiers persist in logs after a session ends, and interviewing the operations team about incident response procedures.
These two workstreams often surface different classes of issues that neither would catch alone. A penetration tester focused purely on exploitability might not think to ask whether a support ticketing integration retains signup IP addresses, while a privacy assessor focused on server configuration might not attempt to actually exploit a subtle authentication logic flaw. The most informative published reports make clear which workstream produced which findings, since it helps readers understand which methodology actually caught each issue.
How Auditor Reputation Gets Built (and Why It Matters)
Because the VPN industry has no single accrediting body akin to a financial audit standard, the credibility of any given engagement rests heavily on the reputation of the auditing firm itself, built up through a track record of work outside the VPN space. Firms with an established history in application security testing, cryptographic review, or compliance-style assurance work across other industries bring a level of external accountability that a firm whose primary client base consists exclusively of VPN providers may not.
This is one reason it’s worth researching the auditing firm itself, not just the report it produced. A firm with a public history of identifying and disclosing serious vulnerabilities across a range of clients — even when that meant delivering unwelcome news — has a stronger incentive to maintain rigorous standards than a firm whose ongoing business depends heavily on a small number of VPN-industry clients being satisfied with the outcome.
Why Some Providers Choose Boutique Firms Over Big-Name Assurance Firms
It is worth noting that the largest, most recognizable audit firm names are not automatically the right fit for every engagement type. Boutique security research firms that specialize specifically in penetration testing of networking and cryptographic protocols sometimes bring deeper technical expertise to the specific problem of testing a VPN tunnel implementation than a broader assurance firm whose staff spend most of their time on financial-controls-style compliance work. Conversely, larger assurance firms with formal process-audit methodologies are often better suited to the no-logs and internal-practice side of an engagement, where structured interview techniques and documentation review matter as much as technical depth.
The strongest engagements often combine both approaches: a specialized penetration-testing firm for the technical exploitability review, paired with a process-focused assurance firm for the no-logs and internal-controls assessment. Providers that commission both types of firms, rather than relying on a single generalist engagement to cover everything, tend to produce more complete and more credible combined reports as a result. When researching a provider’s audit history, it is worth checking whether more than one type of firm has ever been involved, since that variety is itself a meaningful signal of how seriously the provider treats the verification process rather than viewing it as a single box to check.
Our Takeaway
Not all audits are created equal, and the word “audited” on a VPN provider’s marketing page is the beginning of a research process, not the end of one. Understanding the difference between penetration testing and no-logs assessment, paying attention to scope and access depth, and treating remediation history as a signal of process maturity all help separate genuinely rigorous engagements from those designed primarily to generate a press release. In our next report, we’ll walk through how to read an actual published audit document section by section.