SV-214949r610931: The Ubuntu operating system must enforce password complexity by requiring that at least one upper-case character be used. | Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide

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Assessment Title

Rule Text

The Ubuntu operating system must enforce password complexity by requiring that at least one upper-case character be used.

Description

Discussion Text

Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000192V-75449SV-90129

References

DPMS Target Canonical Ubuntu 16.04 LTS DISA DPMS Target Canonical Ubuntu 16.04 LTS 4011

Checks

DISA STIG (Manual Reference)

Verify the Ubuntu operating system enforces password complexity by requiring that at least one upper-case character be used.

Determine if the field "ucredit" is set in the "/etc/security/pwquality.conf" or "/etc/pwquality.conf.d/*.conf" files with the following command:

# grep -i "ucredit" /etc/security/pwquality.conf /etc/pwquality.conf.d/*.conf
ucredit=-1

If the "ucredit" parameter is not equal to "-1", or is commented out, 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.stig.ubuntu1604:def:108
# The Ubuntu operating system must enforce password complexity by requiring that at least one upper-case character be used.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.
#
# MANUAL REVIEW REQUIRED -- the module(s) below could not be reconstructed
# into working code from curated SCC reference data, and are excluded from
# the automated result:
#   - textfilecontent54_object (textfilecontent54_test) -- pwquality:ucredit is -1 or less: <set> composition (base object oval:mil.disa.stig.ubuntu1604:obj:10801, oval:mil.disa.stig.ubuntu1604:obj:10802): member unresolved -- no extractor for field "subexpression"

# package libpam-pwquality is installed
# dpkginfo_object (dpkginfo_test)
test_1() {
  grep -A1 '^Package: libpam-pwquality$' /var/lib/dpkg/status &>/dev/null
}
# The pam_pwquality module is included in common-password
# textfilecontent54_object (textfilecontent54_test)
test_2() {
  grep -Pq '^\s*password\s+(?:(?:required)|(?:requisite))\s+pam_pwquality\.so.*$' '/etc/pam.d/common-password' &>/dev/null
}

if ( test_1 && test_2 ); then
  echo "PASS (automated portion only -- MANUAL REVIEW still required, see notes above)"
else
  echo "FAIL (or see MANUAL REVIEW note above)"
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 Ubuntu password complexity rule (oval:mil.disa.stig.ubuntu1604:def:108)
if dpkg -s libpam-pwquality &> /dev/null && grep -q "^\\s*password\\s+(?:(?:required)|(?:requisite))\\s+pam_pwquality\\.so$" /etc/pam.d/common-password && [ $(grep -c "^\\s*ucredit[\\s]*=[\\s]*(-?\\d+)(?:[\\s]|$)" /etc/security/pwquality.conf) -ge 1 -o $(grep -c "^\\s*ucredit[\\s]*=[\\s]*(-?\\d+)(?:[\\s]|$)" /etc/security/pwquality.conf.d/*.conf) -ge 1 ]; then echo "PASS"; exit 0; else echo "FAIL"; exit 1; fi

Remediation

Configure the Ubuntu operating system to enforce password complexity by requiring that at least one upper-case character be used.

Add or update the following line in the "/etc/security/pwquality.conf" file or a configuration file in the /etc/pwquality.conf.d/ directory to contain the "ucredit" parameter:

ucredit=-1