Linux: Only designated log hosts accepts remote rsyslog messages

# SPDX-FileCopyrightText: 2020 Greenbone AG
# 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-only

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.150165");
  script_version("2023-07-27T05:05:09+0000");
  script_tag(name:"last_modification", value:"2023-07-27 05:05:09 +0000 (Thu, 27 Jul 2023)");
  script_tag(name:"creation_date", value:"2020-03-16 11:10:17 +0000 (Mon, 16 Mar 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: Only designated log hosts accepts remote rsyslog messages");

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

  script_xref(name:"URL", value:"https://linux.die.net/man/5/rsyslog.conf");

  script_xref(name:"Policy", value:"CIS Distribution Independent Linux v2.0.0: 4.2.1.6 Ensure remote rsyslog messages are only accepted on designated log hosts. (Not Scored)");
  script_xref(name:"Policy", value:"CIS CentOS Linux 8 Benchmark v1.0.0: 4.2.1.6 Ensure remote rsyslog messages are only accepted on designated log hosts. (Not Scored)");
  script_xref(name:"Policy", value:"CIS Controls Version 7: 9.2 Ensure Only Approved Ports Protocols and Services Are Running");

  script_tag(name:"summary", value:"Input plugin for plain TCP syslog. Replaces the deprecated -t
option. Can be used like this:

  - $ModLoad imtcp

  - $InputTCPServerRun 514");

  exit(0);
}

include("policy_functions.inc");

cmd = "grep '$ModLoad' /etc/rsyslog.conf, grep '$InputTCPServerRun' /etc/rsyslog.conf";
title = "'$ModLoad imtcp' and '$InputTCPServerRun 514' in /etc/rsyslog.conf";
solution = "Add '$ModLoad imtcp' and '$InputTCPServerRun 514' to /etc/rsyslog.conf";
test_type = "SSH_Cmd";
default = "ModLoad imtcp, InputTCPServerRun 514";

if(get_kb_item("Policy/linux//etc/rsyslog.conf/ERROR")){
  value = "Error";
  compliant = "incomplete";
  comment = "No SSH connection to host";
}else if(get_kb_item("Policy/linux//etc/rsyslog.conf/content/ERROR")){
  value = "Error";
  compliant = "incomplete";
  comment = "Can not read /etc/rsyslog.conf";
}else{
  content = get_kb_item("Policy/linux//etc/rsyslog.conf/content");
  value = egrep(string:content, pattern:"\$(ModLoad\s+imtcp|InputTCPServerRun\s+514)");
  foreach line (split(value)){
    if(line =~ "^\s*#")
      continue;

    if(line =~ "imtcp")
      imtcp = TRUE;

    if(line =~ "InputTCPServerRun")
      InputTCPServerRun = TRUE;
  }

  if(imtcp && InputTCPServerRun)
    compliant = "yes";
  else
    compliant = "no";
}

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);