---
title: "HOST-PAM-009 No Shell Idle Timeout"
canonical: https://openvapt.com/checks/HOST-PAM-009.html
html: https://openvapt.com/checks/HOST-PAM-009.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-PAM-009 No Shell Idle Timeout

Checks that interactive shells log out after at most 15 minutes without input (TMOUT).

- Domain: Server
- Severity: Low
- Control category: Identity and Authentication
- 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: 4.3
- NIST CSF 2.0: PR.PS-01
- CWE: CWE-613
- OWASP Top 10 2021: A07:2021
- NIST SP 800-53 Rev. 5: AC-11, AC-12
- Benchmark topic: Default user shell timeout (CIS Controls v8 4.3) (topic only, no benchmark text)

## Why It Matters

A root shell left open on an unattended terminal, or a forgotten SSH session on a shared workstation, is free privilege for whoever sits down next. TMOUT makes bash and ksh close an idle session automatically; readonly stops users from switching it off.

## How It Detects

Reads /etc/profile, /etc/profile.d/*.sh, /etc/bash.bashrc and /etc/bashrc for a TMOUT=N assignment (optionally readonly, export, typeset -x or declare -x). N from 1 to 900 passes; 0, a larger value or no assignment fails. Incomplete when none of the files can be read.

## How to Fix

Create /etc/profile.d/99-tmout.sh with  TMOUT=900 ; readonly TMOUT ; export TMOUT  (mode 644, owned by root). Sessions that must stay open should use a multiplexer such as tmux with its own lock, not a longer TMOUT. Caution: a readonly TMOUT ends idle interactive shells, including foreground jobs left waiting in them; run long jobs under nohup, systemd-run or a multiplexer.

## How to Verify

```
grep -rE '^\s*(readonly |export )?TMOUT=' /etc/profile /etc/profile.d/ /etc/bash.bashrc /etc/bashrc 2>/dev/null
```

## Learn the Theory

- [P22 Authentication Policy and Package Hygiene](https://openvapt.com/academy/p22.md)

## References

- [Bash Reference Manual, Bash Variables (TMOUT)](https://www.gnu.org/software/bash/manual/html_node/Bash-Variables.html)
- [NIST SP 800-53 Rev. 5, Security and Privacy Controls](https://csrc.nist.gov/pubs/sp/800/53/r5/upd1/final)

## Source Code

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

Run it: `openvapt scan --only HOST-PAM-009`. Read it offline: `openvapt explain HOST-PAM-009`.

---

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