SV-218074r603264: The system default umask for the csh shell must be 077. | Red Hat Enterprise Linux 6 Security Technical Implementation Guide

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Assessment Title

Rule Text

The system default umask for the csh shell must be 077.

Description

Discussion Text

The umask value influences the permissions assigned to files when they are created. A misconfigured umask value could result in files with excessive permissions that can be read and/or written to by unauthorized users.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000366CCE-27034-8SV-50450V-38649

References

DPMS Target Red Hat Enterprise Linux 6 DISA DPMS Target Red Hat Enterprise Linux 6 4046

Checks

OVAL

oval:mil.disa.fso.redhat.rhel6:var:3265 ← xccdf_mil.disa.stig_value_var_accounts_user_umask

DISA STIG (Manual Reference)

Verify the "umask" setting is configured correctly in the "/etc/csh.cshrc" file by running the following command: 

# grep "umask" /etc/csh.cshrc

All output must show the value of "umask" set to 077, as shown in the below: 

# grep "umask" /etc/csh.cshrc
umask 077


If the above command returns no output, or if the umask is configured incorrectly, this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.fso.redhat.rhel6:def:663
# The system default umask for the csh shell must be 077.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# textfilecontent54_object (textfilecontent54_test)
test_1() {
  (sed -En 's/^[\s]*umask[\s]+([^#\s]*)/\1/p' '/etc/csh.cshrc') | grep -qxF '077'
}
# rpminfo_object (rpminfo_test)
test_2() {
  ! ( rpm -q --quiet 'tcsh' &>/dev/null )
}
# file_object (file_test)
test_3() {
  ! ( test -e '/etc/csh.cshrc' &>/dev/null )
}

if ( test_1 || ( test_2 && test_3 ) ); then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# DISA STIG / SCAP compliance check for umask 077 in /etc/csh.cshrc

if [ ! -f "/etc/csh.cshrc" ]; then
  echo "PASS"
  exit 0
fi

if grep -q "^[\s]*umask[\s]+077" /etc/csh.cshrc; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

Remediation

To ensure the default umask for users of the C shell is set properly, add or correct the "umask" setting in "/etc/csh.cshrc" to read as follows: 

umask 077