A world-readable file is a file that any app or process on the device can read, not just the intended application. On Android, this can expose cached requests, usernames, or other user-specific data to malicious software already installed on the device, increasing the chance of theft or recon collection.
What a world-readable file actually means
A world-readable file is a file whose permissions allow any app or process on the device to read it, rather than restricting access to the intended application or user context. The issue is not the file type itself, but the access boundary it fails to enforce.
On mobile platforms, that boundary matters because one app’s local cache can contain data that is harmless in isolation but sensitive when combined with other app state, device metadata, or account identifiers. A world-readable cache turns that local storage into shared exposure.
Why world-readable files are a security problem
The risk is straightforward: if a malicious app is already present on the device, it can enumerate or read files that should have been private. That can expose cached requests, usernames, session-adjacent data, or other user-specific content without needing to break the original application itself.
This is a classic confidentiality failure, and it often comes from overly broad permissions, legacy storage patterns, or assumptions that local files are “safe” because they are not network-accessible. In practice, local read access is still access.
Common ways this issue appears
- Application caches written with permissive file modes.
- Temporary files stored in shared locations instead of app-private storage.
- Debug or diagnostic artifacts left behind in production builds.
- Migration code that preserves old permissions when data is copied or rotated.
The practical concern is that these files may look operationally harmless, yet they can reveal enough context to support reconnaissance, impersonation attempts, or follow-on abuse. NIST Cybersecurity Framework 2.0 is a useful reference point for thinking about this as a protection and exposure issue, while NIST SP 800-53 Rev 5 Security and Privacy Controls reinforces that access control and configuration discipline must extend to stored data, not just interactive access.
How to think about the term in practice
“World-readable” is a permission problem, but it is also a design smell. If data must remain private after it is written, the storage location, file mode, and cleanup behavior all need to be part of the security design, not an afterthought.
For mobile and client software, the safer default is app-private storage with explicit restriction on any file that can carry user data, tokens, requests, logs, or identifiers. Even modest leakage can be enough to aid theft or recon, especially on devices with multiple installed apps.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST CSF 2.0, NIST SP 800-53 Rev 5 and CIS Controls v8 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST CSF 2.0 | PR.DS-01 — Data-at-rest is protected | World-readable files expose stored data through weak protection. |
| Recommendation — Protect local files so only intended app contexts can read them. | ||
| NIST SP 800-53 Rev 5 | AC-6 — Least Privilege | File permissions should limit read access to only authorized subjects. |
| CM-6 — Configuration Settings | Unsafe file modes are a configuration problem that weakens protection. | |
| Recommendation — Apply least-privilege file permissions to restrict local read access. Enforce secure file-mode defaults in application and build configurations. | ||
| CIS Controls v8 | CIS-3 — Data Protection | CIS safeguards address protecting sensitive data at rest on endpoints. |
| Recommendation — Classify local data and protect it with restrictive storage controls. | ||
| ISO/IEC 27001:2022 | A.8.3 — Information access restriction | Restricting file readability aligns with access restriction for information assets. |
| Recommendation — Restrict access to stored information based on need to know. | ||
Related resources from NHI Mgmt Group
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Reviewed and updated by the NHIMG editorial team on September 29, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
