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CIS Ubuntu 14.04 LTS - 5.4.5 Ensure default user shell timeout is 900 seconds or less

DevOps & Security
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Verify TMOUT is set to 900 seconds or less in shell configuration files for idle session timeout

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5.4.5 Ensure default user shell timeout is 900 seconds or less (Scored)

Profile Applicability

  • Level 2 - Server
  • Level 2 - Workstation

Description

The default TMOUT determines the shell timeout for users. The TMOUT value is measured in seconds.

Rationale

Having no timeout value associated with a shell could allow an unauthorized user access to another user's shell session (e.g. user walks away from their computer and doesn't lock the screen). Setting a timeout value at least reduces the risk of this happening.

Audit Procedure

Run the following commands and verify all TMOUT lines returned are 900 or less and at least one exists in each file:

grep "^TMOUT" /etc/bashrc
grep "^TMOUT" /etc/profile

Expected Result

TMOUT=600

Remediation

Edit the /etc/bashrc and /etc/profile files (and the appropriate files for any other shell supported on your system) and add or edit any umask parameters as follows:

TMOUT=600

Default Value

No TMOUT configured by default.

References

  • CIS Controls: 16.4 - Automatically Log Off Users After Standard Period Of Inactivity

Profile

  • Level 2 - Server
  • Level 2 - Workstation