They assume the spreadsheet is temporary when it has already become part of the access control model. Once secrets live in ad hoc files, the organisation loses visibility, auditability, and reliable offboarding. The real issue is not the file format. It is the fact that uncontrolled distribution has replaced governed access.
Why This Matters for Security Teams
Secrets in spreadsheets are rarely a documentation problem. They are a control failure: access is no longer tied to role, purpose, or lifecycle, and the file often becomes the de facto distribution system. That creates hidden privilege, weak offboarding, and no dependable audit trail. Current guidance across the OWASP Non-Human Identity Top 10 and NHI governance work treats uncontrolled secret handling as a lifecycle risk, not a storage-format issue. NHIMG research on the Guide to the Secret Sprawl Challenge shows why: once secrets sprawl across ad hoc locations, security teams lose visibility over where they are copied, who can open them, and whether they ever get removed. In practice, many security teams discover the spreadsheet only after a leak, a contractor exit, or a failed audit rather than through intentional governance.
How It Works in Practice
The operational mistake is assuming that spreadsheet storage is temporary until a proper vault is deployed. In reality, the spreadsheet often becomes the access control layer because teams share it, duplicate it, and rely on it during onboarding, troubleshooting, and incident response. That means the same secret may exist in email, chat exports, downloads, and personal drives long after the original file is forgotten.
Practitioners should treat this as a migration and containment problem:
- Inventory every spreadsheet that contains credentials, tokens, API keys, or certificates.
- Map who can read, edit, download, and forward each file, not just who “owns” it.
- Replace static entries with governed secrets delivery from a dedicated system, aligned to Ultimate Guide to NHIs — Static vs Dynamic Secrets.
- Rotate any secret that has been copied outside controlled storage, then revoke stale versions.
- Use policy and logging that can prove where a secret was accessed, by whom, and when.
That approach is consistent with the Akeyless survey, where only 44% of organisations reported using a dedicated secrets management system and 54% were dissatisfied because not all secrets were secured. The key lesson is that spreadsheets usually persist because they are operationally convenient, not because they are secure. These controls tend to break down in fast-moving engineering teams that share files across multiple collaboration tools because file distribution outpaces access review.
Common Variations and Edge Cases
Tighter secret handling often increases friction during onboarding, incident response, and small-team operations, so organisations must balance speed against control. There is no universal standard for when a spreadsheet must be eliminated immediately versus quarantined during transition, but current guidance suggests treating the file as toxic once it contains reusable production credentials.
Some teams try to compensate with password protection, limited sharing links, or separate tabs for different environments. Those measures can reduce casual exposure, but they do not fix the core issue if secrets still sit in a broad, user-managed document. A spreadsheet may be acceptable as a temporary migration aid for non-production values, yet even that exception should be time-boxed and paired with documented ownership. The moment the file becomes a standing source of truth, it has become part of the access model.
For stronger practical handling, security teams should align spreadsheet cleanup with offboarding, secret rotation, and application inventory reviews. The 52 NHI Breaches Analysis and CI/CD pipeline exploitation case study both reinforce the same pattern: once secrets are copied into unmanaged channels, containment becomes harder than prevention.
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 address the attack and risk surface, while NIST CSF 2.0 and 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-03 | Addresses weak secret lifecycle control when secrets are copied into uncontrolled files. |
| NIST CSF 2.0 | PR.AC-1 | Spreadsheets bypass access governance and create untracked secret distribution. |
| NIST CSF 2.0 | PR.DS-1 | This is fundamentally a data security and leakage problem for sensitive credentials. |
Inventory spreadsheet-held secrets and move them to governed storage with enforced rotation and revocation.
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on June 23, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
