Prevent Login to Accounts With Empty Passwor (ubuntu2404)

이 페이지는 아직 영어로 제공되지 않습니다. 번역 작업 중입니다.
현재 번역 프로젝트에 대한 질문이나 피드백이 있으신 경우 언제든지 연락주시기 바랍니다.

Description

If an account is configured for password authentication but does not have an assigned password, it may be possible to log into the account without authentication. Remove any instances of the nullok in /etc/pam.d/common-{password,auth,account,session,session-noninteractive} to prevent logins with empty passwords.

Rationale

If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# Remediation is applicable only in certain platforms
if ( dpkg-query --show --showformat='${db:Status-Status}' 'libpam-runtime' 2>/dev/null | grep -q '^installed$' && dpkg-query --show --showformat='${db:Status-Status}' 'linux-base' 2>/dev/null | grep -q '^installed$' ); then

conf_name=cac_unix
conf_path="/usr/share/pam-configs"

if [ ! -f "$conf_path"/"$conf_name" ]; then
    if [ -f "$conf_path"/unix ]; then
        if grep -q "$(md5sum "$conf_path"/unix | cut -d ' ' -f 1)" /var/lib/dpkg/info/libpam-runtime.md5sums;then
            cp "$conf_path"/unix "$conf_path"/"$conf_name"
            sed -i 's/Priority: [0-9]\+/Priority: 257\
Conflicts: unix/' "$conf_path"/"$conf_name"
            DEBIAN_FRONTEND=noninteractive pam-auth-update
        else
            echo "Not applicable - checksum of $conf_path/unix does not match the original." >&2
        fi
    else
        echo "Not applicable - $conf_path/unix does not exist" >&2
    fi
fi
config_file="/usr/share/pam-configs/cac_unix"
sed -i '/pam_unix\.so/s/nullok//g' "$config_file"

DEBIAN_FRONTEND=noninteractive pam-auth-update

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi