Linux: minclass in pam_pwquality.so

# Copyright (C) 2020 Greenbone Networks GmbH
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-or-later
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.150266");
  script_version("2022-08-31T10:10:28+0000");
  script_tag(name:"last_modification", value:"2022-08-31 10:10:28 +0000 (Wed, 31 Aug 2022)");
  script_tag(name:"creation_date", value:"2020-06-11 12:44:32 +0000 (Thu, 11 Jun 2020)");
  script_tag(name:"cvss_base", value:"0.0");
  script_tag(name:"cvss_base_vector", value:"AV:L/AC:H/Au:S/C:N/I:N/A:N");
  script_tag(name:"qod", value:"97");

  script_name("Linux: minclass in pam_pwquality.so");

  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2020 Greenbone Networks GmbH");
  script_family("Policy");
  script_dependencies("compliance_tests.nasl", "read_etc_pamd.nasl");
  script_mandatory_keys("Compliance/Launch");

  script_add_preference(name:"Value", type:"entry", value:"3", id:1);

  script_xref(name:"URL", value:"https://linux.die.net/man/8/pam_pwquality");

  script_tag(name:"summary", value:"The pam_pwquality module can be plugged into the password stack
of a given service to provide some plug-in strength-checking for passwords. The code was originally
based on pam_cracklib module and the module is backwards compatible with its options.

  - minclass: The minimum number of required classes of characters for the new password. The default
number is zero. The four classes are digits, upper and lower letters and other characters. The
difference to the credit check is that a specific class if of characters is not required. Instead
N out of four of the classes are required.");

  exit(0);
}

include("policy_functions.inc");

cmd = "grep minclass /etc/pam.d/system-auth /etc/pam.d/password-auth /etc/pam.d/common-password";
title = "Minimum number of required classes of characters for the new password";
solution = "Set minclass=VALUE in /etc/pam.d/common-password, /etc/pam.d/password-auth or /etc/pam.d/system-auth";
test_type = "SSH_Cmd";
default = script_get_preference("Value", id:1);

if(get_kb_item("Policy/linux/etc/pam.d/ERROR")){
  value = "Error";
  compliant = "incomplete";
  comment = "No SSH connection to host possible.";
}else{
  files = make_list("/etc/pam.d/system-auth", "/etc/pam.d/password-auth", "/etc/pam.d/common-password");
  foreach file (files){
    if(get_kb_item("Policy/linux/" + file + "/content/ERROR"))
      continue;

    content = get_kb_item("Policy/linux/" + file + "/content");
    password_required_pam_pwquality = egrep(string:content, pattern:"pam_pwquality.so");
    foreach line (split(password_required_pam_pwquality, keep:FALSE)){
      minclass_match = eregmatch(string:line, pattern:"minclass=([0-9]+)");
      if(minclass_match)
        value = minclass_match[1];
    }
  }

  if(!value){
    value = "None";
    compliant = "no";
    comment = "Could not find minclass option";
  }else{
    compliant = policy_setting_exact_match(value:int(value), set_point:int(default));
  }
}

policy_reporting(result:value, default:default, compliant:compliant, fixtext:solution,
  type:test_type, test:cmd, info:comment);
policy_set_kbs(type:test_type, cmd:cmd, default:default, solution:solution, title:title,
  value:value, compliant:compliant);

exit(0);