---
title: "HOST-FS-015 Files With No Known Owner or Group"
canonical: https://openvapt.com/checks/HOST-FS-015.html
html: https://openvapt.com/checks/HOST-FS-015.html
site: OpenVAPT, https://openvapt.com/
license: OpenVAPT Source-Available Licence 1.3, https://openvapt.com/legal/licence-text.html
modified: 2026-10-14
version: 0.1.0-alpha.6
---

# HOST-FS-015 Files With No Known Owner or Group

Looks for files whose owner or group id no longer appears in /etc/passwd or /etc/group.

- Domain: Server
- Severity: Low
- Control category: Access Control
- Fix effort: low
- CVSS v3.1 vector: `CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N`
- CIS Controls v8: 3.3
- NIST CSF 2.0: PR.AA-05, PR.DS-01
- CWE: CWE-282
- NIST SP 800-53 Rev. 5: AC-2, AC-6, CM-6
- Benchmark topic: No unowned or ungrouped files (CIS Controls v8 3.3) (topic only, no benchmark text)

## Why It Matters

When an account is deleted, its files keep the numeric id. The next account created with that id silently inherits them, which can hand a new user old keys, scripts or cron jobs.

## How It Detects

Reads the numeric ids from /etc/passwd and /etc/group, then walks /etc, /usr/local, /opt, /srv, /var/www, /home and /root (metadata only, up to 20000 files per tree, symlinks not followed) and lists files whose uid or gid is unknown. Unreadable account files make the check incomplete.

## How to Fix

Decide who should own each listed file and apply  chown <user>:<group> <path>, or remove files that belonged to a deleted account after checking their contents.

## How to Verify

```
find /etc /usr/local /opt /srv /var/www /home -xdev \( -nouser -o -nogroup \)  should print nothing.
```

## Learn the Theory

- [P1 Linux Server Hardening](https://openvapt.com/academy/p1.md)
- [P17 Kernel, Filesystem and Boot Hardening](https://openvapt.com/academy/p17.md)

## References

- [NIST SP 800-123, Guide to General Server Security](https://csrc.nist.gov/pubs/sp/800/123/final)
- [passwd(5), Linux man-pages](https://man7.org/linux/man-pages/man5/passwd.5.html)

## Source Code

https://github.com/OpenVAPT/openvapt/blob/574f7f3333c44b75a3c649e2d93a76d507f75adf/internal/checks/host/files_mounts.go

Run it: `openvapt scan --only HOST-FS-015`. Read it offline: `openvapt explain HOST-FS-015`.

---

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