Spreadsheets break down when third-party access scales beyond a handful of users. They do not reliably capture approvals, active entitlements, session state, or removal status, so access reviews become stale and offboarding is missed. In practice, that means organizations can no longer prove who had access, when, or why.
Why This Matters for Security Teams
Third-party access is one of the fastest ways for an organisation to lose visibility over who can reach critical systems, and spreadsheets make that problem worse by turning access control into a manual record-keeping exercise. They rarely stay current with approvals, privilege changes, session duration, or revocation status, so the evidence needed for audits and incident response is always behind reality. That gap is especially dangerous when third parties use service accounts, API keys, or shared credentials.
NHI Management Group’s Ultimate Guide to NHIs notes that 92% of organisations expose NHIs to third parties, which shows how common this exposure has become. Once access is tracked in files rather than systems, teams can no longer reliably answer basic questions like who approved access, whether it is still active, or whether offboarding happened. That is why spreadsheet governance tends to fail first in vendor-heavy environments, not in clean-room labs.
Current guidance from the OWASP Non-Human Identity Top 10 and the NIST Cybersecurity Framework 2.0 both point toward continuous visibility and governed access lifecycle handling, not static lists. In practice, many security teams discover that spreadsheet-managed access is broken only after a vendor account is still active long after the contract ended.
How It Works in Practice
Spreadsheet-based third-party access management usually starts as a convenient tracker for approvals, accounts, and renewal dates. The problem is that access is not a document, it is a living state. As soon as a vendor’s role changes, a token is rotated, a contractor changes projects, or a shared login is reused, the spreadsheet diverges from the actual environment. That creates false confidence during access review and makes remediation dependent on human follow-up rather than enforced control.
Better practice is to treat third-party access as a lifecycle workflow with authoritative system records. That means binding each external identity to an owner, a business justification, an expiry date, and a revocation path. Where possible, use dedicated IAM, PAM, or NHI governance platforms that can record approval, issue short-lived access, and verify removal. For non-human access, this should be aligned with the lifecycle principles described in Ultimate Guide to NHIs — Lifecycle Processes for Managing NHIs and reinforced by the NHI Lifecycle Management Guide.
- Use the spreadsheet, if at all, only as a temporary intake form, not as the source of truth.
- Sync approvals into an identity or ticketing system that can enforce expiry and revocation.
- Require named ownership for every third-party account, key, or integration.
- Validate active access directly against the target system before each review.
- Track removal as a system event, not an email acknowledgement.
This approach works best when access is centrally provisioned and identities are individually assigned. These controls tend to break down when third parties rely on shared credentials, unmanaged API keys, or shadow integrations because there is no reliable system event to reconcile against the spreadsheet.
Common Variations and Edge Cases
Tighter control over third-party access often increases operational overhead, so organisations have to balance auditability against speed of onboarding. That tradeoff becomes sharper in environments with many short-term vendors, development partners, or outsourced support teams. There is no universal standard for this yet, but current guidance suggests that spreadsheet exceptions should be rare and time-boxed, not normalised.
One common edge case is read-only access for auditors or consultants. Even here, spreadsheets fail when access is inherited through group membership or when the same account is reused across multiple engagements. Another is machine-to-machine access, where the real risk is not a human forgetting to update a file but a long-lived secret remaining valid after the relationship ends. NHI Management Group’s Top 10 NHI Issues highlights how excessive privileges and poor visibility compound that risk.
Where organisations are still early in maturity, spreadsheets can be a temporary bridge for inventory discovery, but they should not be used for control decisions. If the environment includes shared accounts, multiple approvers, or contractor-led admin work, the file stops being a reliable record almost immediately. In those cases, the safest answer is to move the control plane into systems that can prove current access state, not just record a historical intent.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and CSA MAESTRO address the attack and risk surface, while NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-01 | Spreadsheet-managed third-party access hides lifecycle and visibility gaps for NHIs. |
| NIST CSF 2.0 | PR.AA-01 | Third-party access needs continuous identity and entitlement assurance, not static records. |
| CSA MAESTRO | MAESTRO-Identity | Agent and third-party access both require lifecycle governance and runtime control. |
Continuously verify external identities, approvals, and active entitlements against system-of-record data.
