nginx 0.6.18 - 1.20.0 1-byte Memory Overwrite Vulnerability

# Copyright (C) 2021 Greenbone Networks GmbH
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# 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
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
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# along with this program; if not, write to the Free Software
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CPE = "cpe:/a:nginx:nginx";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.117455");
  script_version("2022-09-15T10:11:07+0000");
  script_tag(name:"last_modification", value:"2022-09-15 10:11:07 +0000 (Thu, 15 Sep 2022)");
  script_tag(name:"creation_date", value:"2021-05-26 05:58:48 +0000 (Wed, 26 May 2021)");
  script_tag(name:"cvss_base", value:"6.8");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:P/I:P/A:P");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2022-09-14 15:49:00 +0000 (Wed, 14 Sep 2022)");

  script_cve_id("CVE-2021-23017");

  script_tag(name:"qod_type", value:"remote_banner_unreliable");

  script_tag(name:"solution_type", value:"VendorFix");

  script_name("nginx 0.6.18 - 1.20.0 1-byte Memory Overwrite Vulnerability");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2021 Greenbone Networks GmbH");
  script_family("Web Servers");
  script_dependencies("gb_nginx_consolidation.nasl");
  script_mandatory_keys("nginx/detected");

  script_tag(name:"summary", value:"nginx is prone to a 1-byte memory overwrite vulnerability.");

  script_tag(name:"insight", value:"A security issue in nginx resolver was identified, which might
  allow an attacker to cause 1-byte memory overwrite by using a specially crafted DNS response,
  resulting in worker process crash or, potentially, in arbitrary code execution.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable version is present on the target host.");

  script_tag(name:"affected", value:"nginx version 0.6.18 through 1.20.0.

  Note: The issue only affects nginx if the 'resolver' directive is used in the configuration file.
  Further, the attack is only possible if an attacker is able to forge UDP packets from the DNS
  server.");

  script_tag(name:"solution", value:"Update to version 1.20.1, 1.21.0 or later.");

  script_xref(name:"URL", value:"http://mailman.nginx.org/pipermail/nginx-announce/2021/000300.html");

  exit(0);
}

include("host_details.inc");
include("version_func.inc");

if( isnull( port = get_app_port( cpe: CPE ) ) )
  exit( 0 );

if( ! infos = get_app_version_and_location( cpe: CPE, port: port, exit_no_version: TRUE ) )
  exit( 0 );

version = infos["version"];
location = infos["location"];

if( version_in_range( version: version, test_version: "0.6.18", test_version2: "1.20.0" ) ) {
  report = report_fixed_ver( installed_version: version, fixed_version: "1.20.1/1.21.0", install_path: location );
  security_message( port: port, data: report );
  exit( 0 );
}

exit( 99 );